Revert "remove hadoop2 specific handling"

This reverts commit cde6568.

clients/spark/build.sbt

@@ -28,7 +28,8 @@ def generateCoreProject(buildType: BuildType) =
   Project(s"${baseName}-client-${buildType.name}", file(s"core"))
     .settings(
       sharedSettings,
-      assembly / assemblyShadeRules := shadeRules,
+      if (buildType.hadoopFlavour == "hadoop2") hadoop2ShadingSettings
+      else hadoop3ShadingSettings,
       s3UploadSettings,
       settingsToCompileIn("core", buildType.hadoopFlavour),
       semanticdbEnabled := true, // enable SemanticDB
@@ -37,7 +38,8 @@ def generateCoreProject(buildType: BuildType) =
       Compile / PB.targets := Seq(
         scalapb.gen() -> (Compile / sourceManaged).value / "scalapb"
       ),
-      libraryDependencies ++= getSharedLibraryDependencies(buildType),
+      libraryDependencies ++= getSharedLibraryDependencies(buildType)
+        ++ getLibraryDependenciesByHadoopFlavour(buildType.hadoopFlavour),
       testFrameworks += new TestFramework("org.scalameter.ScalaMeterFramework"),
       Test / logBuffered := false,
       // Uncomment to get accurate benchmarks with just "sbt test".
@@ -94,7 +96,6 @@ def getSharedLibraryDependencies(buildType: BuildType): Seq[ModuleID] = {
     "org.apache.hadoop" % "hadoop-aws" % buildType.hadoopVersion % "provided",
     "org.apache.hadoop" % "hadoop-common" % buildType.hadoopVersion % "provided",
     "org.apache.hadoop" % "hadoop-azure" % buildType.hadoopVersion % "provided",
-    "com.amazonaws" % "aws-java-sdk-bundle" % "1.12.194" % "provided",
     "org.json4s" %% "json4s-native" % "3.6.12",
     "org.rogach" %% "scallop" % "4.0.3",
     "com.azure" % "azure-core" % "1.10.0",
@@ -123,6 +124,17 @@ def getSharedLibraryDependencies(buildType: BuildType): Seq[ModuleID] = {
   )
 }
 
+def getLibraryDependenciesByHadoopFlavour(hadoopFlavour: String): Seq[ModuleID] = {
+  if (hadoopFlavour == "hadoop2") {
+    // hadoop-aws provides AWS SDK at version >= 1.7.4.  So declare this
+    // version, but ask to use whatever is provided so we do not
+    // override what it selects.
+    Seq("com.amazonaws" % "aws-java-sdk-bundle" % "1.12.194")
+  } else {
+    Seq("com.amazonaws" % "aws-java-sdk-bundle" % "1.12.194" % "provided")
+  }
+}
+
 def rename(prefix: String) = ShadeRule.rename(prefix -> "io.lakefs.spark.shade.@0")
 
 // We are using the default sbt assembly merge strategy https://github.com/sbt/sbt-assembly#merge-strategy with a change
@@ -146,7 +158,7 @@ lazy val sharedAssemblyMergeStrategy =
     case _ => MergeStrategy.first
   }
 
-lazy val shadeRules = Seq(
+lazy val sharedShadeRules = Seq(
   rename("org.apache.http.**").inAll,
   rename("com.google.protobuf.**").inAll,
   rename("com.google.common.**")
@@ -161,6 +173,12 @@ lazy val shadeRules = Seq(
   rename("reactor.util.**").inAll
 )
 
+lazy val hadoop2ShadeRules = sharedShadeRules ++ Seq(rename("com.amazonaws.**").inAll)
+lazy val hadoop3ShadeRules = sharedShadeRules
+
+lazy val hadoop2ShadingSettings = assembly / assemblyShadeRules := hadoop2ShadeRules
+lazy val hadoop3ShadingSettings = assembly / assemblyShadeRules := hadoop3ShadeRules
+
 // Upload assembly jars to S3
 lazy val s3UploadSettings = Seq(
   s3Upload / mappings := Seq(