fix HandleFactory.packageHandles reuse

With resourcePath like "lib\jrt-fs.jar|java.base|com/sun/Class.class"
the packageHandles cache was never reused since the length of the
lastPkgFragmentRootPath and jarPath never matched.

With this change PackageFragment instances are reused as long as package
does not change

org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/util/HandleFactory.java

@@ -13,8 +13,10 @@
  *******************************************************************************/
 package org.eclipse.jdt.internal.core.util;
 
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Objects;
 
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IProject;
@@ -87,18 +89,14 @@ public Openable createOpenable(String resourcePath, IJavaSearchScope scope) {
 		if ((separatorIndex= resourcePath.indexOf(IJavaSearchScope.JAR_FILE_ENTRY_SEPARATOR)) > -1) {
 			// path to a class file inside a jar
 			// Optimization: cache package fragment root handle and package handles
-			int rootPathLength;
-			PackageFragmentRoot root = null;
-			if (this.lastPkgFragmentRootPath == null
-					|| (rootPathLength = this.lastPkgFragmentRootPath.length()) != resourcePath.length()
-					|| !resourcePath.regionMatches(0, this.lastPkgFragmentRootPath, 0, rootPathLength)) {
-				String jarPath= resourcePath.substring(0, separatorIndex);
-				root= getJarPkgFragmentRoot(resourcePath, separatorIndex, jarPath, scope);
+			String jarPath = resourcePath.substring(0, separatorIndex);
+			if (!Objects.equals(this.lastPkgFragmentRootPath, jarPath)) {
+				PackageFragmentRoot root = getJarPkgFragmentRoot(resourcePath, separatorIndex, jarPath, scope);
 				if (root == null)
 					return null; // match is outside classpath
-				this.lastPkgFragmentRootPath= jarPath;
-				this.lastPkgFragmentRoot= root;
-				this.packageHandles= new HashtableOfArrayToObject(5);
+				this.lastPkgFragmentRootPath = jarPath;
+				this.lastPkgFragmentRoot = root;
+				this.packageHandles = new HashtableOfArrayToObject(5);
 			}
 			// create handle
 			String module = null;
@@ -109,13 +107,12 @@ public Openable createOpenable(String resourcePath, IJavaSearchScope scope) {
 			}
 			String classFilePath= resourcePath.substring(separatorIndex + 1);
 			if (classFilePath.endsWith(TypeConstants.AUTOMATIC_MODULE_NAME))
-				return root;
+				return this.lastPkgFragmentRoot;
 			String[] simpleNames = new Path(classFilePath).segments();
 			String[] pkgName;
 			int length = simpleNames.length-1;
 			if (length > 0) {
-				pkgName = new String[length];
-				System.arraycopy(simpleNames, 0, pkgName, 0, length);
+				pkgName = Arrays.copyOf(simpleNames, length);
 			} else {
 				pkgName = CharOperation.NO_STRINGS;
 			}