diff --git a/.build/runbuild.ps1 b/.build/runbuild.ps1
index 4fad5efe5d..c0204c47a0 100644
--- a/.build/runbuild.ps1
+++ b/.build/runbuild.ps1
@@ -109,6 +109,7 @@ task Init -depends CheckSDK, UpdateLocalSDKVersion -description "This task makes
     Write-Host "Powershell Version: $($PSVersionTable.PSVersion)"
 
     Ensure-Directory-Exists "$artifactsDirectory"
+    Ensure-Directory-Exists "$nugetPackageDirectory" # helpful when adding this path to your nuget sources for local installs
 }
 
 task Restore -description "This task restores the dependencies" {
diff --git a/Directory.Build.targets b/Directory.Build.targets
index b0bcc3b8c3..187d31b921 100644
--- a/Directory.Build.targets
+++ b/Directory.Build.targets
@@ -31,6 +31,7 @@
 
     <DefineConstants>$(DefineConstants);FEATURE_RANDOM_NEXTINT64_NEXTSINGLE</DefineConstants>
     <DefineConstants>$(DefineConstants);FEATURE_SPANFORMATTABLE</DefineConstants>
+    <DefineConstants>$(DefineConstants);FEATURE_SUPPORTEDOSPLATFORMATTRIBUTE</DefineConstants>
 
   </PropertyGroup>
 
diff --git a/TestTargetFramework.props b/TestTargetFramework.props
index 023e64dc36..a98107864f 100644
--- a/TestTargetFramework.props
+++ b/TestTargetFramework.props
@@ -23,7 +23,7 @@
 <Project>
 
   <PropertyGroup>
-    <!-- Changing this setting will allow testing on all target frameworks within Visual Studio 2019.
+    <!-- Changing this setting will allow testing on all target frameworks within Visual Studio.
     Note that the main libraries are multi-targeted, so this has no effect on how they are compiled,
     this setting only affects the test projects. -->
     <!--<TargetFramework>net472</TargetFramework>-->
@@ -38,7 +38,7 @@
 
     <!-- Test Client to DLL target works as follows:
       Test Client       | Target Under Test
-      net8.0            | net6.0
+      net8.0            | net8.0
       net6.0            | net6.0
       net5.0            | netstandard2.1
       net48             | net462
@@ -67,6 +67,7 @@
 
     <!-- We purposely test on EoL frameworks for testing netstandard2.1, but we want to keep this warning in production code. -->
     <CheckEolTargetFramework Condition=" '$(TargetFramework)' == 'net5.0' ">false</CheckEolTargetFramework>
+    <SuppressTfmSupportBuildWarnings Condition=" '$(TargetFramework)' == 'net5.0' ">true</SuppressTfmSupportBuildWarnings>
 
     <NoWarn Label="Nested types should not be visible">$(NoWarn);CA1034</NoWarn>
     <NoWarn Label="Use Literals Where Appropriate">$(NoWarn);CA1802</NoWarn>
diff --git a/src/Lucene.Net.Analysis.Common/Analysis/Hunspell/Dictionary.cs b/src/Lucene.Net.Analysis.Common/Analysis/Hunspell/Dictionary.cs
index e03cc80430..2665f69409 100644
--- a/src/Lucene.Net.Analysis.Common/Analysis/Hunspell/Dictionary.cs
+++ b/src/Lucene.Net.Analysis.Common/Analysis/Hunspell/Dictionary.cs
@@ -1,6 +1,5 @@
 // Lucene version compatibility level 4.10.4
 using J2N;
-using J2N.Collections.Generic.Extensions;
 using J2N.Numerics;
 using J2N.Text;
 using Lucene.Net.Diagnostics;
@@ -726,11 +725,11 @@ internal static string GetDictionaryEncoding(Stream affix)
         internal static readonly IDictionary<string, string> CHARSET_ALIASES = LoadCharsetAliases();
         private static IDictionary<string, string> LoadCharsetAliases() // LUCENENET: Avoid static constructors (see https://github.com/apache/lucenenet/pull/224#issuecomment-469284006)
         {
-            return new Dictionary<string, string>
+            return Collections.AsReadOnly(new Dictionary<string, string>
             {
                 ["microsoft-cp1251"] = "windows-1251",
                 ["TIS620-2533"] = "TIS-620"
-            }.AsReadOnly();
+            });
         }
 
         /// <summary>
diff --git a/src/Lucene.Net.Analysis.Common/Analysis/Util/AbstractAnalysisFactory.cs b/src/Lucene.Net.Analysis.Common/Analysis/Util/AbstractAnalysisFactory.cs
index 5afe7c5c57..9839b027d4 100644
--- a/src/Lucene.Net.Analysis.Common/Analysis/Util/AbstractAnalysisFactory.cs
+++ b/src/Lucene.Net.Analysis.Common/Analysis/Util/AbstractAnalysisFactory.cs
@@ -1,5 +1,4 @@
 // Lucene version compatibility level 4.8.1
-using J2N.Collections.Generic.Extensions;
 using Lucene.Net.Analysis.Core;
 using Lucene.Net.Support;
 using Lucene.Net.Util;
@@ -38,7 +37,7 @@ namespace Lucene.Net.Analysis.Util
     /// The typical lifecycle for a factory consumer is:
     /// <list type="bullet">
     ///     <item><description>Create factory via its constructor (or via XXXFactory.ForName)</description></item>
-    ///     <item><description>(Optional) If the factory uses resources such as files, 
+    ///     <item><description>(Optional) If the factory uses resources such as files,
     ///         <see cref="IResourceLoaderAware.Inform(IResourceLoader)"/> is called to initialize those resources.</description></item>
     ///     <item><description>Consumer calls create() to obtain instances.</description></item>
     /// </list>
@@ -62,7 +61,7 @@ public abstract class AbstractAnalysisFactory
         protected AbstractAnalysisFactory(IDictionary<string, string> args)
         {
             IsExplicitLuceneMatchVersion = false;
-            originalArgs = args.AsReadOnly();
+            originalArgs = Collections.AsReadOnly(args);
             string version = Get(args, LUCENE_MATCH_VERSION_PARAM);
             // LUCENENET TODO: What should we do if the version is null?
             //luceneMatchVersion = version is null ? (LuceneVersion?)null : LuceneVersionHelpers.ParseLeniently(version);
@@ -79,7 +78,7 @@ protected AbstractAnalysisFactory(IDictionary<string, string> args)
         /// <summary>
         /// this method can be called in the <see cref="TokenizerFactory.Create(TextReader)"/>
         /// or <see cref="TokenFilterFactory.Create(TokenStream)"/> methods,
-        /// to inform user, that for this factory a <see cref="m_luceneMatchVersion"/> is required 
+        /// to inform user, that for this factory a <see cref="m_luceneMatchVersion"/> is required
         /// </summary>
         [SuppressMessage("Performance", "CA1822:Mark members as static", Justification = "By design")]
         protected void AssureMatchVersion() // LUCENENET TODO: Remove this method (not used anyway in .NET)
@@ -296,7 +295,7 @@ public virtual ISet<string> GetSet(IDictionary<string, string> args, string name
         }
 
         /// <summary>
-        /// Compiles a pattern for the value of the specified argument key <paramref name="name"/> 
+        /// Compiles a pattern for the value of the specified argument key <paramref name="name"/>
         /// </summary>
         protected Regex GetPattern(IDictionary<string, string> args, string name)
         {
@@ -372,7 +371,7 @@ protected IList<string> GetLines(IResourceLoader loader, string resource)
 
         /// <summary>
         /// Same as <see cref="GetWordSet(IResourceLoader, string, bool)"/>,
-        /// except the input is in snowball format. 
+        /// except the input is in snowball format.
         /// </summary>
         protected CharArraySet GetSnowballWordSet(IResourceLoader loader, string wordFiles, bool ignoreCase)
         {
@@ -428,7 +427,7 @@ private static class SplitFileNameHolder
 
         private const string CLASS_NAME = "class";
 
-        /// <returns> the string used to specify the concrete class name in a serialized representation: the class arg.  
+        /// <returns> the string used to specify the concrete class name in a serialized representation: the class arg.
         ///         If the concrete class name was not specified via a class arg, returns <c>GetType().Name</c>. </returns>
         public virtual string GetClassArg()
         {
@@ -445,4 +444,4 @@ public virtual string GetClassArg()
 
         public virtual bool IsExplicitLuceneMatchVersion { get; set; }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lucene.Net.Analysis.Common/Analysis/Util/AnalysisSPILoader.cs b/src/Lucene.Net.Analysis.Common/Analysis/Util/AnalysisSPILoader.cs
index 5b493f5a09..f362acd0cf 100644
--- a/src/Lucene.Net.Analysis.Common/Analysis/Util/AnalysisSPILoader.cs
+++ b/src/Lucene.Net.Analysis.Common/Analysis/Util/AnalysisSPILoader.cs
@@ -1,5 +1,4 @@
 // Lucene version compatibility level 4.8.1
-using J2N.Collections.Generic.Extensions;
 using Lucene.Net.Support;
 using Lucene.Net.Support.Threading;
 using Lucene.Net.Util;
@@ -98,7 +97,7 @@ public void Reload()
                         services.Add(name, service);
                     }
                 }
-                this.services = services.AsReadOnly();
+                this.services = Collections.AsReadOnly(services);
             }
             finally
             {
@@ -136,4 +135,4 @@ public Type LookupClass(string name)
 
         public ICollection<string> AvailableServices => services.Keys;
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lucene.Net.Analysis.Common/Lucene.Net.Analysis.Common.csproj b/src/Lucene.Net.Analysis.Common/Lucene.Net.Analysis.Common.csproj
index 5a64acc9e1..f832a424e0 100644
--- a/src/Lucene.Net.Analysis.Common/Lucene.Net.Analysis.Common.csproj
+++ b/src/Lucene.Net.Analysis.Common/Lucene.Net.Analysis.Common.csproj
@@ -26,11 +26,11 @@
     <Description>Analyzers for indexing content in different languages and domains for the Lucene.NET full-text search engine library from The Apache Software Foundation.</Description>
     <PackageDocumentationRelativeUrl>analysis-common/overview.html</PackageDocumentationRelativeUrl>
   </PropertyGroup>
-  
+
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Analysis.Common</AssemblyTitle>
     <PackageTags>$(PackageTags);analysis</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <EmbeddedResource Include="**/*.rslp" Exclude="bin/**/*;obj/**/*" Label="RSLP Test Data" />
diff --git a/src/Lucene.Net.Analysis.Kuromoji/Lucene.Net.Analysis.Kuromoji.csproj b/src/Lucene.Net.Analysis.Kuromoji/Lucene.Net.Analysis.Kuromoji.csproj
index 463cd17cc3..4d7dbd38bc 100644
--- a/src/Lucene.Net.Analysis.Kuromoji/Lucene.Net.Analysis.Kuromoji.csproj
+++ b/src/Lucene.Net.Analysis.Kuromoji/Lucene.Net.Analysis.Kuromoji.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Analysis.Kuromoji</AssemblyTitle>
     <PackageTags>$(PackageTags);analysis;japanese</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <EmbeddedResource Include="**/*.txt" Exclude="bin/**/*;obj/**/*" Label="Text Test Data" />
diff --git a/src/Lucene.Net.Analysis.Morfologik/Lucene.Net.Analysis.Morfologik.csproj b/src/Lucene.Net.Analysis.Morfologik/Lucene.Net.Analysis.Morfologik.csproj
index fe435a6e05..6c1316b3b6 100644
--- a/src/Lucene.Net.Analysis.Morfologik/Lucene.Net.Analysis.Morfologik.csproj
+++ b/src/Lucene.Net.Analysis.Morfologik/Lucene.Net.Analysis.Morfologik.csproj
@@ -26,11 +26,11 @@
     <Description>Analyzer for dictionary stemming, built-in Polish dictionary for the Lucene.NET full-text search engine library from The Apache Software Foundation.</Description>
     <PackageDocumentationRelativeUrl>analysis-morfologik/Lucene.Net.Analysis.Morfologik.html</PackageDocumentationRelativeUrl>
   </PropertyGroup>
-  
+
   <Import Project="$(SolutionDir).build/nuget.props" />
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Analysis.Morfologik</AssemblyTitle>
     <RootNamespace>Lucene.Net.Analysis</RootNamespace>
@@ -39,7 +39,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <Compile Remove="Properties\AssemblyInfo.cs" />
diff --git a/src/Lucene.Net.Analysis.OpenNLP/Lucene.Net.Analysis.OpenNLP.csproj b/src/Lucene.Net.Analysis.OpenNLP/Lucene.Net.Analysis.OpenNLP.csproj
index c8a8759bdc..7ca0c855e7 100644
--- a/src/Lucene.Net.Analysis.OpenNLP/Lucene.Net.Analysis.OpenNLP.csproj
+++ b/src/Lucene.Net.Analysis.OpenNLP/Lucene.Net.Analysis.OpenNLP.csproj
@@ -32,7 +32,7 @@
   <PropertyGroup>
     <!-- Currently, IKVM doesn't officially support building NetFX on anything but Windows, so we skip it for contributors who may be on various platforms.
         We can remove the condition once that has been addressed. See: https://github.com/ikvmnet/ikvm-maven/issues/49 -->
-    <TargetFrameworks>net6.0</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0</TargetFrameworks>
     <TargetFrameworks Condition="$([MSBuild]::IsOsPlatform('Windows'))">$(TargetFrameworks);net472</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Analysis.OpenNLP</AssemblyTitle>
diff --git a/src/Lucene.Net.Analysis.Phonetic/Language/Bm/Lang.cs b/src/Lucene.Net.Analysis.Phonetic/Language/Bm/Lang.cs
index 57e7cdbfe2..863213baef 100644
--- a/src/Lucene.Net.Analysis.Phonetic/Language/Bm/Lang.cs
+++ b/src/Lucene.Net.Analysis.Phonetic/Language/Bm/Lang.cs
@@ -1,7 +1,7 @@
 // commons-codec version compatibility level: 1.9
 using J2N;
-using J2N.Collections.Generic.Extensions;
 using J2N.Text;
+using Lucene.Net.Support;
 using System;
 using System.Collections.Generic;
 using System.IO;
@@ -218,7 +218,7 @@ public static Lang LoadFromResource(string languageRulesResourceName, Languages
 
         private Lang(IList<LangRule> rules, Languages languages)
         {
-            this.rules = rules.AsReadOnly();
+            this.rules = Collections.AsReadOnly(rules);
             this.languages = languages;
         }
 
diff --git a/src/Lucene.Net.Analysis.Phonetic/Language/Bm/Rule.cs b/src/Lucene.Net.Analysis.Phonetic/Language/Bm/Rule.cs
index 97130dcf3d..fb2b53fbd6 100644
--- a/src/Lucene.Net.Analysis.Phonetic/Language/Bm/Rule.cs
+++ b/src/Lucene.Net.Analysis.Phonetic/Language/Bm/Rule.cs
@@ -1,6 +1,5 @@
 // commons-codec version compatibility level: 1.9
 using J2N;
-using J2N.Collections.Generic.Extensions;
 using J2N.Text;
 using Lucene.Net.Support;
 using Lucene.Net.Util;
@@ -150,10 +149,10 @@ private static IDictionary<NameType, IDictionary<RuleType, IDictionary<string, I
                         rs["common"] = ParseRules(CreateScanner(s, rt, "common"), CreateResourceName(s, rt, "common"));
                     }
 
-                    rts[rt] = rs.AsReadOnly();
+                    rts[rt] = Collections.AsReadOnly(rs);
                 }
 
-                rules[s] = rts.AsReadOnly();
+                rules[s] = Collections.AsReadOnly(rts);
             }
             return rules;
         }
@@ -217,7 +216,7 @@ private static TextReader CreateScanner(NameType nameType, RuleType rt, string l
 
         private static TextReader CreateScanner(string lang)
         {
-            string resName = string.Format("{0}.txt", lang); 
+            string resName = string.Format("{0}.txt", lang);
             Stream rulesIS = typeof(Languages).FindAndGetManifestResourceStream(resName);
 
             if (rulesIS is null)
@@ -869,7 +868,7 @@ public virtual bool PatternAndContextMatches(ICharSequence input, int i)
         /// <param name="i">The int position within the input.</param>
         /// <returns><c>true</c> if the pattern and left/right context match, <c>false</c> otherwise.</returns>
         // LUCENENET specific
-        public virtual bool PatternAndContextMatches(string input, int i) 
+        public virtual bool PatternAndContextMatches(string input, int i)
         {
             if (i < 0)
             {
@@ -940,7 +939,7 @@ public virtual bool PatternAndContextMatches(StringBuilder input, int i)
 
     public sealed class Phoneme : IPhonemeExpr
     {
-        // LUCENENET: It is no longer good practice to use binary serialization. 
+        // LUCENENET: It is no longer good practice to use binary serialization.
         // See: https://github.com/dotnet/corefx/issues/23584#issuecomment-325724568
 #if FEATURE_SERIALIZABLE
         [Serializable]
diff --git a/src/Lucene.Net.Analysis.Phonetic/Lucene.Net.Analysis.Phonetic.csproj b/src/Lucene.Net.Analysis.Phonetic/Lucene.Net.Analysis.Phonetic.csproj
index 2270760887..6edefcfe05 100644
--- a/src/Lucene.Net.Analysis.Phonetic/Lucene.Net.Analysis.Phonetic.csproj
+++ b/src/Lucene.Net.Analysis.Phonetic/Lucene.Net.Analysis.Phonetic.csproj
@@ -30,7 +30,7 @@
   <Import Project="$(SolutionDir).build/nuget.props" />
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Analysis.Phonetic</AssemblyTitle>
     <PackageTags>$(PackageTags);analysis;soundex;double;metaphone;sounds;like;beider;morse;cologne;caverphone;nysiis;match;rating</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <EmbeddedResource Include="Language\*.txt" />
diff --git a/src/Lucene.Net.Analysis.SmartCn/Lucene.Net.Analysis.SmartCn.csproj b/src/Lucene.Net.Analysis.SmartCn/Lucene.Net.Analysis.SmartCn.csproj
index a5015f2d16..dc850a399a 100644
--- a/src/Lucene.Net.Analysis.SmartCn/Lucene.Net.Analysis.SmartCn.csproj
+++ b/src/Lucene.Net.Analysis.SmartCn/Lucene.Net.Analysis.SmartCn.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Analysis.SmartCn</AssemblyTitle>
     <PackageTags>$(PackageTags);analysis;chinese;smart</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <EmbeddedResource Include="Hhmm/*.mem" Label="Dict Test Data" />
diff --git a/src/Lucene.Net.Analysis.Stempel/Lucene.Net.Analysis.Stempel.csproj b/src/Lucene.Net.Analysis.Stempel/Lucene.Net.Analysis.Stempel.csproj
index a394d18288..dca9b4a6f5 100644
--- a/src/Lucene.Net.Analysis.Stempel/Lucene.Net.Analysis.Stempel.csproj
+++ b/src/Lucene.Net.Analysis.Stempel/Lucene.Net.Analysis.Stempel.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Analysis.Stempel</AssemblyTitle>
     <PackageTags>$(PackageTags);analysis;polish</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <EmbeddedResource Include="Pl\*.tbl;Pl\*.txt" />
diff --git a/src/Lucene.Net.Benchmark/Lucene.Net.Benchmark.csproj b/src/Lucene.Net.Benchmark/Lucene.Net.Benchmark.csproj
index 250ca43a37..ac73b98930 100644
--- a/src/Lucene.Net.Benchmark/Lucene.Net.Benchmark.csproj
+++ b/src/Lucene.Net.Benchmark/Lucene.Net.Benchmark.csproj
@@ -26,11 +26,11 @@
     <Description>System for benchmarking the Lucene.NET full-text search engine library from The Apache Software Foundation.</Description>
     <PackageDocumentationRelativeUrl>benchmark/Lucene.Net.Benchmarks.html</PackageDocumentationRelativeUrl>
   </PropertyGroup>
-  
+
   <Import Project="$(SolutionDir).build/nuget.props" />
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Benchmark</AssemblyTitle>
     <PackageTags>$(PackageTags);benchmark</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\dotnet\Lucene.Net.ICU\Lucene.Net.ICU.csproj" />
diff --git a/src/Lucene.Net.Classification/Lucene.Net.Classification.csproj b/src/Lucene.Net.Classification/Lucene.Net.Classification.csproj
index 3a8b15646c..ef3e8b72bc 100644
--- a/src/Lucene.Net.Classification/Lucene.Net.Classification.csproj
+++ b/src/Lucene.Net.Classification/Lucene.Net.Classification.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Classification</AssemblyTitle>
     <PackageTags>$(PackageTags);classification</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\Lucene.Net\Lucene.Net.csproj" />
diff --git a/src/Lucene.Net.Codecs/Lucene.Net.Codecs.csproj b/src/Lucene.Net.Codecs/Lucene.Net.Codecs.csproj
index 1db2df0782..38c977d06e 100644
--- a/src/Lucene.Net.Codecs/Lucene.Net.Codecs.csproj
+++ b/src/Lucene.Net.Codecs/Lucene.Net.Codecs.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Codecs</AssemblyTitle>
     <PackageTags>$(PackageTags);codec</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\Lucene.Net\Lucene.Net.csproj" />
diff --git a/src/Lucene.Net.Demo/Lucene.Net.Demo.csproj b/src/Lucene.Net.Demo/Lucene.Net.Demo.csproj
index 4381bbb968..4c616682ec 100644
--- a/src/Lucene.Net.Demo/Lucene.Net.Demo.csproj
+++ b/src/Lucene.Net.Demo/Lucene.Net.Demo.csproj
@@ -22,20 +22,20 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <!-- Demo is deployed through the dotnet/tools/lucene-cli package -->
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Demo</AssemblyTitle>
     <Description>Simple example code for the Lucene.Net full-text search engine library from The Apache Software Foundation.</Description>
     <PackageTags>$(PackageTags);demo</PackageTags>
     <DocumentationFile>bin\$(Configuration)\$(TargetFramework)\$(AssemblyName).xml</DocumentationFile>
-    
+
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
     <NoWarn Label="Remove unused parameter">$(NoWarn);IDE0060</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\Lucene.Net\Lucene.Net.csproj" />
diff --git a/src/Lucene.Net.Expressions/JS/JavascriptCompiler.cs b/src/Lucene.Net.Expressions/JS/JavascriptCompiler.cs
index 0b9c7943c1..7dea0c0a40 100644
--- a/src/Lucene.Net.Expressions/JS/JavascriptCompiler.cs
+++ b/src/Lucene.Net.Expressions/JS/JavascriptCompiler.cs
@@ -1,5 +1,4 @@
-using J2N.Collections.Generic.Extensions;
-using J2N.Text;
+using J2N.Text;
 using Antlr.Runtime;
 using Antlr.Runtime.Tree;
 using Lucene.Net.Queries.Function;
@@ -97,7 +96,7 @@ private static MethodInfo GetMethod(Type type, string method, Type[] parms)
 
         private readonly IDictionary<string, MethodInfo> functions;
 
-        
+
 
         private ILGenerator gen;
         private AssemblyBuilder asmBuilder;
@@ -202,7 +201,7 @@ private void BeginCompile()
             dynamicType = modBuilder.DefineType(COMPILED_EXPRESSION_CLASS,
                 TypeAttributes.AnsiClass | TypeAttributes.AutoClass | TypeAttributes.Public | TypeAttributes.Class |
                 TypeAttributes.BeforeFieldInit | TypeAttributes.AutoLayout, EXPRESSION_TYPE);
-            
+
             ConstructorBuilder constructorBuilder = dynamicType.DefineConstructor(MethodAttributes.Public,
                 CallingConventions.HasThis,
                 new[] { typeof(string), typeof(string[]) });
@@ -634,7 +633,7 @@ private static IDictionary<string, MethodInfo> LoadDefaultFunctions() // LUCENEN
             {
                 throw Error.Create("Cannot resolve function", e);
             }
-            return map.AsReadOnly();
+            return Collections.AsReadOnly(map);
         }
 
         private static Type GetType(string typeName)
diff --git a/src/Lucene.Net.Expressions/Lucene.Net.Expressions.csproj b/src/Lucene.Net.Expressions/Lucene.Net.Expressions.csproj
index d32f09fd6e..0c62f265fd 100644
--- a/src/Lucene.Net.Expressions/Lucene.Net.Expressions.csproj
+++ b/src/Lucene.Net.Expressions/Lucene.Net.Expressions.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Expressions</AssemblyTitle>
     <PackageTags>$(PackageTags);expression</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\Lucene.Net.Queries\Lucene.Net.Queries.csproj" />
@@ -51,13 +51,13 @@
     <PackageReference Include="System.Net.Http" Version="$(SystemNetHttpPackageVersion)" />
     <PackageReference Include="System.Text.RegularExpressions" Version="$(SystemTextRegularExpressionsPackageVersion)" />
   </ItemGroup>
-  
+
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.1' ">
     <PackageReference Include="System.Reflection.Emit" Version="$(SystemReflectionEmitPackageVersion)" />
     <PackageReference Include="System.Reflection.Emit.ILGeneration" Version="$(SystemReflectionEmitILGenerationPackageVersion)" />
     <PackageReference Include="System.Reflection.TypeExtensions" Version="$(SystemReflectionTypeExtensionsPackageVersion)" />
   </ItemGroup>
-  
+
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
     <PackageReference Include="System.Reflection.Emit" Version="$(SystemReflectionEmitPackageVersion)" />
     <PackageReference Include="System.Reflection.Emit.ILGeneration" Version="$(SystemReflectionEmitILGenerationPackageVersion)" />
diff --git a/src/Lucene.Net.Facet/Lucene.Net.Facet.csproj b/src/Lucene.Net.Facet/Lucene.Net.Facet.csproj
index 2406b72f5a..ec61433d6d 100644
--- a/src/Lucene.Net.Facet/Lucene.Net.Facet.csproj
+++ b/src/Lucene.Net.Facet/Lucene.Net.Facet.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Facet</AssemblyTitle>
     <PackageTags>$(PackageTags);facet;faceted</PackageTags>
diff --git a/src/Lucene.Net.Grouping/Lucene.Net.Grouping.csproj b/src/Lucene.Net.Grouping/Lucene.Net.Grouping.csproj
index 9d11ecd511..1a0c3c2ada 100644
--- a/src/Lucene.Net.Grouping/Lucene.Net.Grouping.csproj
+++ b/src/Lucene.Net.Grouping/Lucene.Net.Grouping.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Grouping</AssemblyTitle>
     <PackageTags>$(PackageTags);grouping;group</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\Lucene.Net\Lucene.Net.csproj" />
diff --git a/src/Lucene.Net.Highlighter/Lucene.Net.Highlighter.csproj b/src/Lucene.Net.Highlighter/Lucene.Net.Highlighter.csproj
index a1a2ac2c0c..ba96f09504 100644
--- a/src/Lucene.Net.Highlighter/Lucene.Net.Highlighter.csproj
+++ b/src/Lucene.Net.Highlighter/Lucene.Net.Highlighter.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Highlighter</AssemblyTitle>
     <PackageTags>$(PackageTags);highlight;highlighter</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\Lucene.Net.Memory\Lucene.Net.Memory.csproj" />
diff --git a/src/Lucene.Net.Join/Lucene.Net.Join.csproj b/src/Lucene.Net.Join/Lucene.Net.Join.csproj
index a85cd5ae8e..86ba93956f 100644
--- a/src/Lucene.Net.Join/Lucene.Net.Join.csproj
+++ b/src/Lucene.Net.Join/Lucene.Net.Join.csproj
@@ -28,19 +28,19 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <RootNamespace>Lucene.Net.Search.Join</RootNamespace>
-    
+
     <AssemblyTitle>Lucene.Net.Join</AssemblyTitle>
     <PackageTags>$(PackageTags);join</PackageTags>
     <DocumentationFile>bin\$(Configuration)\$(TargetFramework)\$(AssemblyName).xml</DocumentationFile>
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\Lucene.Net.Grouping\Lucene.Net.Grouping.csproj" />
diff --git a/src/Lucene.Net.Memory/Lucene.Net.Memory.csproj b/src/Lucene.Net.Memory/Lucene.Net.Memory.csproj
index d373b3dc76..433641f028 100644
--- a/src/Lucene.Net.Memory/Lucene.Net.Memory.csproj
+++ b/src/Lucene.Net.Memory/Lucene.Net.Memory.csproj
@@ -28,17 +28,17 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
-    
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+
     <AssemblyTitle>Lucene.Net.Memory</AssemblyTitle>
     <PackageTags>$(PackageTags);memory</PackageTags>
     <DocumentationFile>bin\$(Configuration)\$(TargetFramework)\$(AssemblyName).xml</DocumentationFile>
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\Lucene.Net\Lucene.Net.csproj" />
diff --git a/src/Lucene.Net.Misc/Lucene.Net.Misc.csproj b/src/Lucene.Net.Misc/Lucene.Net.Misc.csproj
index 42e2679762..4aa45cc0cb 100644
--- a/src/Lucene.Net.Misc/Lucene.Net.Misc.csproj
+++ b/src/Lucene.Net.Misc/Lucene.Net.Misc.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Misc</AssemblyTitle>
     <PackageTags>$(PackageTags);miscellaneous</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <Compile Remove="Store\*" />
diff --git a/src/Lucene.Net.Queries/Lucene.Net.Queries.csproj b/src/Lucene.Net.Queries/Lucene.Net.Queries.csproj
index 90833c84bf..d8718a3c45 100644
--- a/src/Lucene.Net.Queries/Lucene.Net.Queries.csproj
+++ b/src/Lucene.Net.Queries/Lucene.Net.Queries.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Queries</AssemblyTitle>
     <PackageTags>$(PackageTags);query;queries</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\Lucene.Net\Lucene.Net.csproj" />
diff --git a/src/Lucene.Net.QueryParser/Lucene.Net.QueryParser.csproj b/src/Lucene.Net.QueryParser/Lucene.Net.QueryParser.csproj
index fe8ba4d3ba..9111ebd2bb 100644
--- a/src/Lucene.Net.QueryParser/Lucene.Net.QueryParser.csproj
+++ b/src/Lucene.Net.QueryParser/Lucene.Net.QueryParser.csproj
@@ -28,22 +28,22 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <RootNamespace>Lucene.Net.QueryParsers</RootNamespace>
-    
+
     <AssemblyTitle>Lucene.Net.QueryParser</AssemblyTitle>
     <PackageTags>$(PackageTags);query;queryparser</PackageTags>
     <DocumentationFile>bin\$(Configuration)\$(TargetFramework)\$(AssemblyName).xml</DocumentationFile>
-    
+
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
     <NoWarn Label="Remove unused parameter">$(NoWarn);IDE0060</NoWarn>
   </PropertyGroup>
 
-  
-  
+
+
   <ItemGroup>
     <ProjectReference Include="..\Lucene.Net.Analysis.Common\Lucene.Net.Analysis.Common.csproj" />
     <ProjectReference Include="..\Lucene.Net.Queries\Lucene.Net.Queries.csproj" />
diff --git a/src/Lucene.Net.Replicator/IndexRevision.cs b/src/Lucene.Net.Replicator/IndexRevision.cs
index 69ba7b48cb..83f8d725cc 100644
--- a/src/Lucene.Net.Replicator/IndexRevision.cs
+++ b/src/Lucene.Net.Replicator/IndexRevision.cs
@@ -2,6 +2,7 @@
 using Lucene.Net.Diagnostics;
 using Lucene.Net.Index;
 using Lucene.Net.Store;
+using Lucene.Net.Support;
 using System;
 using System.Collections.Generic;
 using System.Globalization;
@@ -79,14 +80,14 @@ public static IDictionary<string, IList<RevisionFile>> RevisionFiles(IndexCommit
             }
             revisionFiles.Add(CreateRevisionFile(segmentsFile, dir)); // segments_N must be last
 
-            return new Dictionary<string, IList<RevisionFile>>
+            return Collections.AsReadOnly(new Dictionary<string, IList<RevisionFile>>
             {
                 { SOURCE, revisionFiles }
-            }.AsReadOnly();
+            });
         }
-   
+
         /// <summary>
-        /// Returns a string representation of a revision's version from the given 
+        /// Returns a string representation of a revision's version from the given
         /// <see cref="IndexCommit"/>
         /// </summary>
         public static string RevisionVersion(IndexCommit commit)
@@ -149,4 +150,4 @@ public override string ToString()
             return "IndexRevision version=" + Version + " files=" + SourceFiles;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lucene.Net.Replicator/Lucene.Net.Replicator.csproj b/src/Lucene.Net.Replicator/Lucene.Net.Replicator.csproj
index 9d721ac034..585813dcf0 100644
--- a/src/Lucene.Net.Replicator/Lucene.Net.Replicator.csproj
+++ b/src/Lucene.Net.Replicator/Lucene.Net.Replicator.csproj
@@ -30,7 +30,7 @@
   <Import Project="$(SolutionDir).build/nuget.props" />
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Replicator</AssemblyTitle>
     <PackageTags>$(PackageTags);files;replication;replicate</PackageTags>
diff --git a/src/Lucene.Net.Replicator/ReplicationClient.cs b/src/Lucene.Net.Replicator/ReplicationClient.cs
index e002b3a6fd..ae735c576a 100644
--- a/src/Lucene.Net.Replicator/ReplicationClient.cs
+++ b/src/Lucene.Net.Replicator/ReplicationClient.cs
@@ -1,8 +1,8 @@
 using J2N;
-using J2N.Collections.Generic.Extensions;
 using J2N.Threading;
 using Lucene.Net.Diagnostics;
 using Lucene.Net.Store;
+using Lucene.Net.Support;
 using Lucene.Net.Support.Threading;
 using Lucene.Net.Util;
 using System;
@@ -56,7 +56,7 @@ private class ReplicationThread : ThreadJob
             internal readonly CountdownEvent stop = new CountdownEvent(1);
 
             /// <summary>
-            /// 
+            ///
             /// </summary>
             /// <param name="intervalMillis">The interval in milliseconds.</param>
             /// <param name="threadName">The thread name.</param>
@@ -206,7 +206,7 @@ private void DoUpdate()
                             output = directory.CreateOutput(file.FileName, IOContext.DEFAULT);
 
                             CopyBytes(output, input);
-                            
+
                             cpFiles.Add(file.FileName);
                             // TODO add some validation, on size / checksum
                         }
@@ -230,7 +230,7 @@ private void DoUpdate()
                     finally
                     {
                         if (!notify)
-                        { 
+                        {
                             // cleanup after ourselves
                             IOUtils.Dispose(sourceDirectory.Values);
                             factory.CleanupSession(session.Id);
@@ -247,7 +247,7 @@ private void DoUpdate()
                 if (notify && !disposed)
                 { // no use to notify if we are closed already
                     // LUCENENET specific - pass the copiedFiles as read only
-                    handler.RevisionReady(session.Version, session.SourceFiles, copiedFiles.AsReadOnly(), sourceDirectory);
+                    handler.RevisionReady(session.Version, session.SourceFiles, Collections.AsReadOnly(copiedFiles), sourceDirectory);
                 }
             }
             finally
@@ -451,7 +451,7 @@ public override string ToString()
         /// is running or not.
         /// </summary>
         /// <exception cref="IOException"></exception>
-        public virtual void UpdateNow() 
+        public virtual void UpdateNow()
         {
             EnsureOpen();
 
@@ -467,8 +467,8 @@ public virtual void UpdateNow()
             }
         }
 
-        /// <summary> 
-        /// Gets or sets the <see cref="Util.InfoStream"/> to use for logging messages. 
+        /// <summary>
+        /// Gets or sets the <see cref="Util.InfoStream"/> to use for logging messages.
         /// </summary>
         public virtual InfoStream InfoStream
         {
@@ -519,9 +519,9 @@ public interface ISourceDirectoryFactory
         Directory GetDirectory(string sessionId, string source); //throws IOException;
 
         /// <summary>
-        /// Called to denote that the replication actions for this session were finished and the directory is no longer needed. 
+        /// Called to denote that the replication actions for this session were finished and the directory is no longer needed.
         /// </summary>
         /// <exception cref="IOException"></exception>
         void CleanupSession(string sessionId);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lucene.Net.Sandbox/Lucene.Net.Sandbox.csproj b/src/Lucene.Net.Sandbox/Lucene.Net.Sandbox.csproj
index 2dcb6620eb..3dd75428c7 100644
--- a/src/Lucene.Net.Sandbox/Lucene.Net.Sandbox.csproj
+++ b/src/Lucene.Net.Sandbox/Lucene.Net.Sandbox.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Sandbox</AssemblyTitle>
     <PackageTags>$(PackageTags);sandbox</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\Lucene.Net\Lucene.Net.csproj" />
diff --git a/src/Lucene.Net.Spatial/Lucene.Net.Spatial.csproj b/src/Lucene.Net.Spatial/Lucene.Net.Spatial.csproj
index 616b22b98d..d65a374244 100644
--- a/src/Lucene.Net.Spatial/Lucene.Net.Spatial.csproj
+++ b/src/Lucene.Net.Spatial/Lucene.Net.Spatial.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Spatial</AssemblyTitle>
     <PackageTags>$(PackageTags);spatial;geo;geospatial;2d</PackageTags>
@@ -39,7 +39,7 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\Lucene.Net\Lucene.Net.csproj" />
@@ -47,7 +47,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Spatial4n" Version="$(Spatial4nPackageVersion)" /> 
+    <PackageReference Include="Spatial4n" Version="$(Spatial4nPackageVersion)" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/Lucene.Net.Spatial/Prefix/Tree/SpatialPrefixTree.cs b/src/Lucene.Net.Spatial/Prefix/Tree/SpatialPrefixTree.cs
index b60118bf81..5d95a05475 100644
--- a/src/Lucene.Net.Spatial/Prefix/Tree/SpatialPrefixTree.cs
+++ b/src/Lucene.Net.Spatial/Prefix/Tree/SpatialPrefixTree.cs
@@ -1,5 +1,5 @@
-using J2N.Collections.Generic.Extensions;
-using Lucene.Net.Diagnostics;
+using Lucene.Net.Diagnostics;
+using Lucene.Net.Support;
 using Spatial4n.Context;
 using Spatial4n.Shapes;
 using System;
@@ -191,7 +191,7 @@ protected internal virtual Cell GetCell(IPoint p, int level)
         /// ~20-25% fewer cells.
         /// </param>
         /// <returns>a set of cells (no dups), sorted, immutable, non-null</returns>
-        public virtual IList<Cell> GetCells(IShape? shape, int detailLevel, bool inclParents, 
+        public virtual IList<Cell> GetCells(IShape? shape, int detailLevel, bool inclParents,
             bool simplify)
         {
             //TODO consider an on-demand iterator -- it won't build up all cells in memory.
@@ -214,8 +214,8 @@ public virtual IList<Cell> GetCells(IShape? shape, int detailLevel, bool inclPar
         /// descends.
         /// </remarks>
         /// <exception cref="ArgumentNullException"><paramref name="cell"/> is <c>null</c>.</exception>
-        private bool RecursiveGetCells(Cell cell, IShape? shape, int detailLevel, 
-            bool inclParents, bool simplify, 
+        private bool RecursiveGetCells(Cell cell, IShape? shape, int detailLevel,
+            bool inclParents, bool simplify,
             IList<Cell> result)
         {
             // LUCENENET specific - added guard clause
@@ -286,7 +286,7 @@ public virtual IList<Cell> GetCells(IPoint p, int detailLevel, bool inclParents)
             Cell cell = GetCell(p, detailLevel);
             if (!inclParents)
             {
-                return new[] { cell }.AsReadOnly();
+                return Collections.AsReadOnly(new[] { cell });
             }
             string endToken = cell.TokenString;
             if (Debugging.AssertsEnabled) Debugging.Assert(endToken.Length == detailLevel);
diff --git a/src/Lucene.Net.Suggest/Lucene.Net.Suggest.csproj b/src/Lucene.Net.Suggest/Lucene.Net.Suggest.csproj
index f23c686671..4f16d4efe1 100644
--- a/src/Lucene.Net.Suggest/Lucene.Net.Suggest.csproj
+++ b/src/Lucene.Net.Suggest/Lucene.Net.Suggest.csproj
@@ -28,9 +28,9 @@
   </PropertyGroup>
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Suggest</AssemblyTitle>
     <PackageTags>$(PackageTags);suggest;suggestion</PackageTags>
@@ -38,7 +38,7 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\Lucene.Net.Analysis.Common\Lucene.Net.Analysis.Common.csproj" />
diff --git a/src/Lucene.Net.TestFramework/Lucene.Net.TestFramework.csproj b/src/Lucene.Net.TestFramework/Lucene.Net.TestFramework.csproj
index 712ec3b0e2..2a94042190 100644
--- a/src/Lucene.Net.TestFramework/Lucene.Net.TestFramework.csproj
+++ b/src/Lucene.Net.TestFramework/Lucene.Net.TestFramework.csproj
@@ -30,20 +30,20 @@
   <Import Project="$(SolutionDir).build/nuget.props" />
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.TestFramework</AssemblyTitle>
     <RootNamespace>Lucene.Net</RootNamespace>
     <PackageTags>$(PackageTags);testframework;test;framework;nunit</PackageTags>
     <DocumentationFile>bin\$(Configuration)\$(TargetFramework)\$(AssemblyName).xml</DocumentationFile>
-    
-    
+
+
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
     <NoWarn Label="Collection initialization can be simplified">$(NoWarn);IDE0028</NoWarn>
   </PropertyGroup>
 
-  
-  
+
+
   <ItemGroup>
     <None Remove="Util\europarl.lines.txt.gz" />
     <EmbeddedResource Include="Util\europarl.lines.txt.gz" />
@@ -71,12 +71,12 @@
     <Reference Include="System.Numerics" />
     <Reference Include="System.ServiceModel" />
   </ItemGroup>
-  
+
   <ItemGroup>
     <!--  Note that some of the APIs we use to test Lucene.Net are internal because they are only meant to
           make porting tests from Java easier. This means that every Lucene.Net test project requires
           InternalsVisibleTo, now and in the future to keep these APIs from public view. -->
-    
+
     <InternalsVisibleTo Include="Lucene.Net.Tests._A-D" />
     <InternalsVisibleTo Include="Lucene.Net.Tests._E-I" />
     <InternalsVisibleTo Include="Lucene.Net.Tests._I-J" />
@@ -84,7 +84,7 @@
     <InternalsVisibleTo Include="Lucene.Net.Tests._T-Z" />
 
     <InternalsVisibleTo Include="Lucene.Net.Tests.AllProjects" />
-    
+
     <InternalsVisibleTo Include="Lucene.Net.Tests.Analysis.Common" />
     <InternalsVisibleTo Include="Lucene.Net.Tests.Analysis.Kuromoji" />
     <InternalsVisibleTo Include="Lucene.Net.Tests.Analysis.Morfologik" />
@@ -92,7 +92,7 @@
     <InternalsVisibleTo Include="Lucene.Net.Tests.Analysis.Phonetic" />
     <InternalsVisibleTo Include="Lucene.Net.Tests.Analysis.SmartCn" />
     <InternalsVisibleTo Include="Lucene.Net.Tests.Analysis.Stempel" />
-    
+
     <InternalsVisibleTo Include="Lucene.Net.Tests.Benchmark" />
     <InternalsVisibleTo Include="Lucene.Net.Tests.Classification" />
     <InternalsVisibleTo Include="Lucene.Net.Tests.Cli" />
@@ -116,4 +116,4 @@
     <InternalsVisibleTo Include="Lucene.Net.Tests.TestFramework.DependencyInjection" />
   </ItemGroup>
 
-</Project>
\ No newline at end of file
+</Project>
diff --git a/src/Lucene.Net/Codecs/Lucene3x/Lucene3xSegmentInfoReader.cs b/src/Lucene.Net/Codecs/Lucene3x/Lucene3xSegmentInfoReader.cs
index cc86c6acf3..0b344b2228 100644
--- a/src/Lucene.Net/Codecs/Lucene3x/Lucene3xSegmentInfoReader.cs
+++ b/src/Lucene.Net/Codecs/Lucene3x/Lucene3xSegmentInfoReader.cs
@@ -1,13 +1,12 @@
-using J2N.Collections.Generic.Extensions;
 using Lucene.Net.Diagnostics;
+using Lucene.Net.Support;
 using System;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.Globalization;
+using System.Runtime.CompilerServices;
 using JCG = J2N.Collections.Generic;
 using CompoundFileDirectory = Lucene.Net.Store.CompoundFileDirectory;
 using Directory = Lucene.Net.Store.Directory;
-using System.Runtime.CompilerServices;
 
 namespace Lucene.Net.Codecs.Lucene3x
 {
@@ -41,7 +40,7 @@ namespace Lucene.Net.Codecs.Lucene3x
     /// <summary>
     /// Lucene 3x implementation of <see cref="SegmentInfoReader"/>.
     /// <para/>
-    /// @lucene.experimental 
+    /// @lucene.experimental
     /// </summary>
     [Obsolete("Only for reading existing 3.x indexes")]
     public class Lucene3xSegmentInfoReader : SegmentInfoReader
@@ -292,7 +291,7 @@ private SegmentCommitInfo ReadLegacySegmentInfo(Directory dir, int format, Index
                 }
             }
 
-            SegmentInfo info = new SegmentInfo(dir, version, name, docCount, isCompoundFile, null, diagnostics, attributes.AsReadOnly());
+            SegmentInfo info = new SegmentInfo(dir, version, name, docCount, isCompoundFile, null, diagnostics, Collections.AsReadOnly(attributes));
             info.SetFiles(files);
 
             SegmentCommitInfo infoPerCommit = new SegmentCommitInfo(info, delCount, delGen, -1);
@@ -314,9 +313,9 @@ private SegmentInfo ReadUpgradedSegmentInfo(string name, Directory dir, IndexInp
 
             ISet<string> files = input.ReadStringSet();
 
-            SegmentInfo info = new SegmentInfo(dir, version, name, docCount, isCompoundFile, null, diagnostics, attributes.AsReadOnly());
+            SegmentInfo info = new SegmentInfo(dir, version, name, docCount, isCompoundFile, null, diagnostics, Collections.AsReadOnly(attributes));
             info.SetFiles(files);
             return info;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lucene.Net/Codecs/Lucene42/Lucene42FieldInfosReader.cs b/src/Lucene.Net/Codecs/Lucene42/Lucene42FieldInfosReader.cs
index 5c53f0072f..f3c448bdd3 100644
--- a/src/Lucene.Net/Codecs/Lucene42/Lucene42FieldInfosReader.cs
+++ b/src/Lucene.Net/Codecs/Lucene42/Lucene42FieldInfosReader.cs
@@ -1,5 +1,5 @@
-using J2N.Collections.Generic.Extensions;
-using J2N.Numerics;
+using J2N.Numerics;
+using Lucene.Net.Support;
 using System;
 using System.Collections.Generic;
 
@@ -56,8 +56,8 @@ public override FieldInfos Read(Directory directory, string segmentName, string
             bool success = false;
             try
             {
-                CodecUtil.CheckHeader(input, Lucene42FieldInfosFormat.CODEC_NAME, 
-                                            Lucene42FieldInfosFormat.FORMAT_START, 
+                CodecUtil.CheckHeader(input, Lucene42FieldInfosFormat.CODEC_NAME,
+                                            Lucene42FieldInfosFormat.FORMAT_START,
                                             Lucene42FieldInfosFormat.FORMAT_CURRENT);
 
                 int size = input.ReadVInt32(); //read in the size
@@ -99,8 +99,8 @@ public override FieldInfos Read(Directory directory, string segmentName, string
                     DocValuesType docValuesType = GetDocValuesType(input, (byte)(val & 0x0F));
                     DocValuesType normsType = GetDocValuesType(input, (byte)((val.TripleShift(4)) & 0x0F));
                     IDictionary<string, string> attributes = input.ReadStringStringMap();
-                    infos[i] = new FieldInfo(name, isIndexed, fieldNumber, storeTermVector, 
-                        omitNorms, storePayloads, indexOptions, docValuesType, normsType, attributes.AsReadOnly());
+                    infos[i] = new FieldInfo(name, isIndexed, fieldNumber, storeTermVector,
+                        omitNorms, storePayloads, indexOptions, docValuesType, normsType, Collections.AsReadOnly(attributes));
                 }
 
                 CodecUtil.CheckEOF(input);
@@ -149,4 +149,4 @@ private static DocValuesType GetDocValuesType(IndexInput input, byte b)
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lucene.Net/Codecs/Lucene46/Lucene46FieldInfosReader.cs b/src/Lucene.Net/Codecs/Lucene46/Lucene46FieldInfosReader.cs
index 0c41a05eba..83b9cd7b95 100644
--- a/src/Lucene.Net/Codecs/Lucene46/Lucene46FieldInfosReader.cs
+++ b/src/Lucene.Net/Codecs/Lucene46/Lucene46FieldInfosReader.cs
@@ -1,5 +1,5 @@
-using J2N.Collections.Generic.Extensions;
-using J2N.Numerics;
+using J2N.Numerics;
+using Lucene.Net.Support;
 using System.Collections.Generic;
 
 namespace Lucene.Net.Codecs.Lucene46
@@ -36,7 +36,7 @@ namespace Lucene.Net.Codecs.Lucene46
     /// <summary>
     /// Lucene 4.6 FieldInfos reader.
     /// <para/>
-    /// @lucene.experimental 
+    /// @lucene.experimental
     /// </summary>
     /// <seealso cref="Lucene46FieldInfosFormat"/>
     internal sealed class Lucene46FieldInfosReader : FieldInfosReader
@@ -97,7 +97,7 @@ public override FieldInfos Read(Directory directory, string segmentName, string
                     DocValuesType normsType = GetDocValuesType(input, (byte)((val.TripleShift(4)) & 0x0F));
                     long dvGen = input.ReadInt64();
                     IDictionary<string, string> attributes = input.ReadStringStringMap();
-                    infos[i] = new FieldInfo(name, isIndexed, fieldNumber, storeTermVector, omitNorms, storePayloads, indexOptions, docValuesType, normsType, attributes.AsReadOnly());
+                    infos[i] = new FieldInfo(name, isIndexed, fieldNumber, storeTermVector, omitNorms, storePayloads, indexOptions, docValuesType, normsType, Collections.AsReadOnly(attributes));
                     infos[i].DocValuesGen = dvGen;
                 }
 
@@ -156,4 +156,4 @@ private static DocValuesType GetDocValuesType(IndexInput input, byte b)
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lucene.Net/Index/BaseCompositeReader.cs b/src/Lucene.Net/Index/BaseCompositeReader.cs
index 3bcdb1ca68..c9bb921749 100644
--- a/src/Lucene.Net/Index/BaseCompositeReader.cs
+++ b/src/Lucene.Net/Index/BaseCompositeReader.cs
@@ -1,4 +1,4 @@
-using J2N.Collections.Generic.Extensions;
+using Lucene.Net.Support;
 using System;
 using System.Collections.Generic;
 
@@ -36,7 +36,7 @@ namespace Lucene.Net.Index
     /// as documents are added to and deleted from an index.  Clients should thus not
     /// rely on a given document having the same number between sessions.
     ///
-    /// <para/><b>NOTE</b>: 
+    /// <para/><b>NOTE</b>:
     /// <see cref="IndexReader"/> instances are completely thread
     /// safe, meaning multiple threads can call any of its methods,
     /// concurrently.  If your application requires external
@@ -71,7 +71,7 @@ public abstract class BaseCompositeReader<R> : CompositeReader
         protected BaseCompositeReader(R[] subReaders)
         {
             this.subReaders = subReaders;
-            this.subReadersList = ((IndexReader[])subReaders).AsReadOnly(); // LUCENENET: Work around generic casting from R to IndexWriter
+            this.subReadersList = Collections.AsReadOnly((IndexReader[])subReaders); // LUCENENET: Work around generic casting from R to IndexWriter
             starts = new int[subReaders.Length + 1]; // build starts array
             int maxDoc = 0, numDocs = 0;
             for (int i = 0; i < subReaders.Length; i++)
@@ -215,4 +215,4 @@ protected internal override sealed IList<IndexReader> GetSequentialSubReaders()
             return subReadersList;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lucene.Net/Index/CompositeReaderContext.cs b/src/Lucene.Net/Index/CompositeReaderContext.cs
index 205a6be28a..59f9ea72b1 100644
--- a/src/Lucene.Net/Index/CompositeReaderContext.cs
+++ b/src/Lucene.Net/Index/CompositeReaderContext.cs
@@ -1,5 +1,5 @@
-using J2N.Collections.Generic.Extensions;
-using Lucene.Net.Diagnostics;
+using Lucene.Net.Diagnostics;
+using Lucene.Net.Support;
 using System.Collections.Generic;
 using JCG = J2N.Collections.Generic;
 
@@ -56,7 +56,7 @@ internal CompositeReaderContext(CompositeReader reader, IList<IndexReaderContext
         private CompositeReaderContext(CompositeReaderContext parent, CompositeReader reader, int ordInParent, int docbaseInParent, IList<IndexReaderContext> children, IList<AtomicReaderContext> leaves)
             : base(parent, ordInParent, docbaseInParent)
         {
-            this.children = children.AsReadOnly();
+            this.children = Collections.AsReadOnly(children);
             this.leaves = leaves;
             this.reader = reader;
         }
@@ -130,4 +130,4 @@ internal IndexReaderContext Build(CompositeReaderContext parent, IndexReader rea
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lucene.Net/Index/MergePolicy.cs b/src/Lucene.Net/Index/MergePolicy.cs
index 577abba5f5..5423ba3190 100644
--- a/src/Lucene.Net/Index/MergePolicy.cs
+++ b/src/Lucene.Net/Index/MergePolicy.cs
@@ -1,5 +1,5 @@
-using J2N.Collections.Generic.Extensions;
-using Lucene.Net.Diagnostics;
+using Lucene.Net.Diagnostics;
+using Lucene.Net.Support;
 using Lucene.Net.Support.Threading;
 using Lucene.Net.Util;
 using System;
@@ -56,7 +56,7 @@ namespace Lucene.Net.Index
     /// then return the necessary merges.</para>
     ///
     /// <para>Note that the policy can return more than one merge at
-    /// a time.  In this case, if the writer is using 
+    /// a time.  In this case, if the writer is using
     /// <see cref="SerialMergeScheduler"/>, the merges will be run
     /// sequentially but if it is using
     /// <see cref="ConcurrentMergeScheduler"/> they will be run concurrently.</para>
@@ -190,7 +190,7 @@ public virtual IList<AtomicReader> GetMergeReaders()
                         readers.Add(reader);
                     }
                 }
-                return readers.AsReadOnly();
+                return Collections.AsReadOnly(readers);
             }
 
             /// <summary>
@@ -450,7 +450,7 @@ public class MergeSpecification
             public IList<OneMerge> Merges { get; private set; }
 
             /// <summary>
-            /// Sole constructor.  Use 
+            /// Sole constructor.  Use
             /// <see cref="Add(OneMerge)"/> to add merges.
             /// </summary>
             public MergeSpecification()
@@ -488,7 +488,7 @@ public virtual string SegString(Directory dir)
         /// Exception thrown if there are any problems while
         /// executing a merge.
         /// </summary>
-        // LUCENENET: It is no longer good practice to use binary serialization. 
+        // LUCENENET: It is no longer good practice to use binary serialization.
         // See: https://github.com/dotnet/corefx/issues/23584#issuecomment-325724568
 #if FEATURE_SERIALIZABLE_EXCEPTIONS
         [Serializable]
@@ -544,7 +544,7 @@ protected MergeException(SerializationInfo info, StreamingContext context)
         /// <c>false</c>.  Normally this exception is
         /// privately caught and suppresed by <see cref="IndexWriter"/>.
         /// </summary>
-        // LUCENENET: It is no longer good practice to use binary serialization. 
+        // LUCENENET: It is no longer good practice to use binary serialization.
         // See: https://github.com/dotnet/corefx/issues/23584#issuecomment-325724568
 #if FEATURE_SERIALIZABLE_EXCEPTIONS
         [Serializable]
@@ -736,7 +736,7 @@ public virtual bool UseCompoundFile(SegmentInfos infos, SegmentCommitInfo merged
         }
 
         /// <summary>
-        /// Return the byte size of the provided 
+        /// Return the byte size of the provided
         /// <see cref="SegmentCommitInfo"/>, pro-rated by percentage of
         /// non-deleted documents is set.
         /// </summary>
@@ -763,7 +763,7 @@ protected bool IsMerged(SegmentInfos infos, SegmentCommitInfo info)
 #pragma warning disable 612, 618
                 && !info.Info.HasSeparateNorms
 #pragma warning restore 612, 618
-                && info.Info.Dir == w.Directory 
+                && info.Info.Dir == w.Directory
                 && UseCompoundFile(infos, info) == info.Info.UseCompoundFile;
         }
 
@@ -812,4 +812,4 @@ public double MaxCFSSegmentSizeMB
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lucene.Net/Index/SegmentCommitInfo.cs b/src/Lucene.Net/Index/SegmentCommitInfo.cs
index e8a5fec42d..5ebf8ae023 100644
--- a/src/Lucene.Net/Index/SegmentCommitInfo.cs
+++ b/src/Lucene.Net/Index/SegmentCommitInfo.cs
@@ -99,7 +99,7 @@ public SegmentCommitInfo(SegmentInfo info, int delCount, long delGen, long field
 
         /// <summary>
         /// Returns the per generation updates files. </summary>
-        public virtual IDictionary<long, ISet<string>> UpdatesFiles => genUpdatesFiles.AsReadOnly();
+        public virtual IDictionary<long, ISet<string>> UpdatesFiles => Collections.AsReadOnly(genUpdatesFiles);
 
         /// <summary>
         /// Sets the updates file names per generation. Does not deep clone the map. </summary>
@@ -289,4 +289,4 @@ public virtual object Clone()
             return other;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Lucene.Net/Lucene.Net.csproj b/src/Lucene.Net/Lucene.Net.csproj
index b04cb5b042..c4c163d392 100644
--- a/src/Lucene.Net/Lucene.Net.csproj
+++ b/src/Lucene.Net/Lucene.Net.csproj
@@ -22,9 +22,9 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <Import Project="$(SolutionDir).build/nuget.props" />
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net</AssemblyTitle>
     <Description>Lucene.Net is a full-text search engine library capable of advanced text analysis, indexing, and searching. It can be used to easily add search capabilities to applications. Lucene.Net is a C# port of the popular Java Lucene search engine framework from The Apache Software Foundation, targeted at .NET Framework and .NET Core users.</Description>
@@ -36,7 +36,7 @@
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
-  
+
 
   <PropertyGroup Label="NuGet Package File Paths">
     <LuceneNetDotNetDir>$(SolutionDir)src\dotnet\</LuceneNetDotNetDir>
@@ -100,7 +100,7 @@
     <InternalsVisibleTo Include="Lucene.Net.Suggest" />
 
     <InternalsVisibleTo Include="Lucene.Net.TestFramework" />
-    
+
     <InternalsVisibleTo Include="Lucene.Net.Tests._A-D" />
     <InternalsVisibleTo Include="Lucene.Net.Tests._E-I" />
     <InternalsVisibleTo Include="Lucene.Net.Tests._I-J" />
diff --git a/src/Lucene.Net/Store/NativeFSLockFactory.cs b/src/Lucene.Net/Store/NativeFSLockFactory.cs
index 5935a3ecf7..a38d866174 100644
--- a/src/Lucene.Net/Store/NativeFSLockFactory.cs
+++ b/src/Lucene.Net/Store/NativeFSLockFactory.cs
@@ -1,9 +1,9 @@
 using Lucene.Net.Support.IO;
+using Lucene.Net.Support.Threading;
 using Lucene.Net.Util;
 using System;
-using System.IO;
 using System.Collections.Generic;
-using Lucene.Net.Support.Threading;
+using System.IO;
 
 namespace Lucene.Net.Store
 {
@@ -625,7 +625,7 @@ public override string ToString()
     }
 
     // Uses FileStream locking of file pages.
-#if NET6_0
+#if FEATURE_SUPPORTEDOSPLATFORMATTRIBUTE
     [System.Runtime.Versioning.SupportedOSPlatform("windows")]
 #endif
     internal class NativeFSLock : Lock
@@ -832,4 +832,4 @@ public static void Lock(this FileStream stream, long position, long length)
         }
     }
 #endif
-}
\ No newline at end of file
+}
diff --git a/src/Lucene.Net/Support/Collections.cs b/src/Lucene.Net/Support/Collections.cs
index b7bb6ef4d9..87d33daa7a 100644
--- a/src/Lucene.Net/Support/Collections.cs
+++ b/src/Lucene.Net/Support/Collections.cs
@@ -88,7 +88,7 @@ public static IComparer<T> ReverseOrder<T>(IComparer<T> cmp)
 
         public static IDictionary<TKey, TValue> SingletonMap<TKey, TValue>(TKey key, TValue value)
         {
-            return new Dictionary<TKey, TValue> { { key, value } }.AsReadOnly();
+            return AsReadOnly(new Dictionary<TKey, TValue> { { key, value } });
         }
 
 
@@ -213,6 +213,16 @@ public static string ToString(object obj, CultureInfo culture)
             return ToString(obj);
         }
 
+        public static ReadOnlyList<T> AsReadOnly<T>(IList<T> list)
+        {
+            return new ReadOnlyList<T>(list);
+        }
+
+        public static ReadOnlyDictionary<TKey, TValue> AsReadOnly<TKey, TValue>(IDictionary<TKey, TValue> dictionary)
+        {
+            return new ReadOnlyDictionary<TKey, TValue>(dictionary);
+        }
+
         #region Nested Types
 
         #region ReverseComparer
diff --git a/src/dotnet/Lucene.Net.ICU/Lucene.Net.ICU.csproj b/src/dotnet/Lucene.Net.ICU/Lucene.Net.ICU.csproj
index 827d421e01..c805100438 100644
--- a/src/dotnet/Lucene.Net.ICU/Lucene.Net.ICU.csproj
+++ b/src/dotnet/Lucene.Net.ICU/Lucene.Net.ICU.csproj
@@ -30,7 +30,7 @@
   <Import Project="$(SolutionDir).build/nuget.props" />
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.ICU</AssemblyTitle>
     <PackageTags>$(PackageTags);icu;international;unicode</PackageTags>
@@ -39,7 +39,7 @@
     <DefineConstants>$(DefineConstants);FEATURE_BREAKITERATOR</DefineConstants>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <Compile Include="..\..\Lucene.Net.Analysis.Common\Analysis\Th\**\*.cs" LinkBase="Analysis\Th" />
diff --git a/src/dotnet/Lucene.Net.Replicator.AspNetCore/Lucene.Net.Replicator.AspNetCore.csproj b/src/dotnet/Lucene.Net.Replicator.AspNetCore/Lucene.Net.Replicator.AspNetCore.csproj
index e415034aaa..a40185d2ce 100644
--- a/src/dotnet/Lucene.Net.Replicator.AspNetCore/Lucene.Net.Replicator.AspNetCore.csproj
+++ b/src/dotnet/Lucene.Net.Replicator.AspNetCore/Lucene.Net.Replicator.AspNetCore.csproj
@@ -23,9 +23,9 @@
 
   <!-- For now, we are not deploying this to NuGet.org -->
   <!--<Import Project="$(SolutionDir).build/nuget.props" />-->
-  
+
   <PropertyGroup>
-    <TargetFrameworks>net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
+    <TargetFrameworks>net8.0;net6.0;netstandard2.1;netstandard2.0;net462</TargetFrameworks>
 
     <AssemblyTitle>Lucene.Net.Replicator.AspNetCore</AssemblyTitle>
     <Description>AspNetCore integration of Lucene.Net.Replicator for the Lucene.Net full-text search engine library from The Apache Software Foundation.</Description>
@@ -34,12 +34,12 @@
     <NoWarn>$(NoWarn);1591;1573</NoWarn>
   </PropertyGroup>
 
-  
+
 
   <ItemGroup>
     <ProjectReference Include="..\..\Lucene.Net.Replicator\Lucene.Net.Replicator.csproj" />
   </ItemGroup>
-  
+
   <ItemGroup>
     <PackageReference Include="Microsoft.AspNetCore.Http.Abstractions" Version="$(MicrosoftAspNetCoreHttpAbstractionsPackageVersion)" />