feat: have class URIs use their original source name

org.eclipse.jdt.ls.core/plugin.xml

@@ -225,4 +225,10 @@
          id="org.eclipse.jdt.core.javanature">
       </requires-nature>
    </extension>
+
+   <extension point="org.eclipse.core.contenttype.contentTypes">
+      <file-association
+         content-type="org.eclipse.jdt.core.javaDerivedSource"
+         file-extensions="kt,scala,groovy,clj"/>
+   </extension>
 </plugin>

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/JDTUtils.java

@@ -54,7 +54,6 @@
 import org.eclipse.core.runtime.jobs.ISchedulingRule;
 import org.eclipse.jdt.core.CompletionProposal;
 import org.eclipse.jdt.core.Flags;
-
 import org.eclipse.jdt.core.IAnnotatable;
 import org.eclipse.jdt.core.IAnnotation;
 import org.eclipse.jdt.core.IBuffer;
@@ -106,7 +105,6 @@
 import org.eclipse.jdt.core.dom.SingleVariableDeclaration;
 import org.eclipse.jdt.core.dom.SuperConstructorInvocation;
 import org.eclipse.jdt.core.dom.Type;
-
 import org.eclipse.jdt.core.dom.VariableDeclarationFragment;
 import org.eclipse.jdt.core.manipulation.CoreASTProvider;
 import org.eclipse.jdt.core.manipulation.SharedASTProviderCore;
@@ -147,6 +145,7 @@
 
 /**
  * General utilities for working with JDT APIs
+ *
  * @author Gorkem Ercan
  *
  */
@@ -298,10 +297,10 @@ static ICompilationUnit getFakeCompilationUnit(URI uri, IProgressMonitor monitor
 				public IBuffer createBuffer(ICompilationUnit workingCopy) {
 					return new DocumentAdapter(workingCopy, path);
 				}
- 			};
- 			try {
- 				return owner.newWorkingCopy(fileName, new IClasspathEntry[] { JavaRuntime.getDefaultJREContainerEntry() }, monitor);
- 			} catch (JavaModelException e) {
+			};
+			try {
+				return owner.newWorkingCopy(fileName, new IClasspathEntry[] { JavaRuntime.getDefaultJREContainerEntry() }, monitor);
+			} catch (JavaModelException e) {
 				return null;
 			}
 		}
@@ -432,9 +431,13 @@ public static IClassFile resolveClassFile(String uriString){
 	 * @param uri with 'jdt' scheme
 	 * @return class file
 	 */
-	public static IClassFile resolveClassFile(URI uri){
+	public static IClassFile resolveClassFile(URI uri) {
 		if (uri != null && JDT_SCHEME.equals(uri.getScheme()) && "contents".equals(uri.getAuthority())) {
 			String handleId = uri.getQuery();
+			int idx = handleId.indexOf("&element=");
+			if (idx != -1) {
+				handleId = handleId.substring(0, idx);
+			}
 			IJavaElement element = JavaCore.create(handleId);
 			IClassFile cf = (IClassFile) element.getAncestor(IJavaElement.CLASS_FILE);
 			return cf;
@@ -891,7 +894,25 @@ public static String toUri(IClassFile classFile) {
 		String jarName = classFile.getParent().getParent().getElementName();
 		String uriString = null;
 		try {
-			uriString = new URI(JDT_SCHEME, "contents", PATH_SEPARATOR + jarName + PATH_SEPARATOR + packageName + PATH_SEPARATOR + classFile.getElementName(), classFile.getHandleIdentifier(), null).toASCIIString();
+			String elementName = classFile.getElementName();
+			// Use the original source file name if available
+			String sourceFileName = SourceFileAttributeReader.getSourceFileName(classFile);
+			String fileName = sourceFileName == null ? elementName : sourceFileName;
+			StringBuilder pathBuilder = new StringBuilder();
+			pathBuilder.append(PATH_SEPARATOR).append(jarName);
+			if (packageName != null && !packageName.isBlank()) {
+				pathBuilder.append(PATH_SEPARATOR).append(packageName);
+			}
+			pathBuilder.append(PATH_SEPARATOR).append(fileName);
+
+			String handleIdentifier = classFile.getHandleIdentifier();
+			StringBuilder query = new StringBuilder(handleIdentifier);
+			if (!handleIdentifier.contains(elementName)) {
+				//Add the element name to the query so decompilers can detect it (looking at you module-info.class!)
+				query.append("&element=").append(elementName);
+			}
+			uriString = new URI(JDT_SCHEME, "contents", pathBuilder.toString(), query.toString(), null).toASCIIString();
+
 		} catch (URISyntaxException e) {
 			JavaLanguageServerPlugin.logException("Error generating URI for class ", e);
 		}
@@ -1168,26 +1189,26 @@ public static IResource findResource(URI uri, Function<URI, IResource[]> resourc
 			}
 		}
 		switch(resources.length) {
-		case 0:
-			return null;
-		case 1:
-			return resources[0];
-		default://several candidates if a linked resource was created before the real project was configured
+			case 0:
+				return null;
+			case 1:
+				return resources[0];
+			default://several candidates if a linked resource was created before the real project was configured
 				IResource resource = null;
 				for (IResource f : resources) {
-				//delete linked resource
-				if (ProjectsManager.getDefaultProject().equals(f.getProject())) {
-					try {
-						f.delete(true, null);
-					} catch (CoreException e) {
+					//delete linked resource
+					if (ProjectsManager.getDefaultProject().equals(f.getProject())) {
+						try {
+							f.delete(true, null);
+						} catch (CoreException e) {
 							JavaLanguageServerPlugin.logException(e.getMessage(), e);
+						}
 					}
-				}
-				//find closest project containing that file, in case of nested projects
+					//find closest project containing that file, in case of nested projects
 					if (resource == null || f.getProjectRelativePath().segmentCount() < resource.getProjectRelativePath().segmentCount()) {
 						resource = f;
+					}
 				}
-			}
 				return resource;
 		}
 	}
@@ -1970,3 +1991,4 @@ public static CompilationUnit getAst(ITypeRoot typeRoot, IProgressMonitor monito
 	}
 
 }
+

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/SourceFileAttributeReader.java

@@ -0,0 +1,85 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Red Hat Inc. and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Red Hat Inc. - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.jdt.ls.core.internal;
+
+import org.eclipse.core.runtime.CoreException;
+import org.eclipse.jdt.core.IClassFile;
+import org.eclipse.jdt.core.util.IClassFileReader;
+import org.eclipse.jdt.core.util.ISourceAttribute;
+import org.eclipse.jdt.internal.core.util.ClassFileReader;
+
+/**
+ * Utility class to read the SourceFile attribute from class files.
+ * The SourceFile attribute contains the name of the source file from which
+ * the class was compiled (e.g., "OkHttpClient.kt" for Kotlin classes).
+ */
+public class SourceFileAttributeReader {
+
+	private SourceFileAttributeReader() {
+		// Utility class - no instantiation
+	}
+
+	/**
+	 * Gets the source file name from the SourceFile attribute of the given class file.
+	 *
+	 * @param classFile the class file to read
+	 * @return the source file name (e.g., "OkHttpClient.kt", "MyClass.java"),
+	 *         or null if the attribute is not present or cannot be read
+	 */
+	public static String getSourceFileName(IClassFile classFile) {
+		if (classFile == null) {
+			return null;
+		}
+		try {
+			return getSourceFileName(classFile.getBytes());
+		} catch (CoreException e) {
+			JavaLanguageServerPlugin.logException("Error reading class file bytes", e);
+			return null;
+		}
+	}
+
+	/**
+	 * Gets the source file name from the SourceFile attribute of the given class file bytes.
+	 *
+	 * @param classFileBytes the raw bytes of the class file
+	 * @return the source file name (e.g., "OkHttpClient.kt", "MyClass.java"),
+	 *         or null if the attribute is not present or cannot be read
+	 */
+	public static String getSourceFileName(byte[] classFileBytes) {
+		if (classFileBytes == null || classFileBytes.length == 0) {
+			return null;
+		}
+
+		try {
+			// Use Eclipse JDT's class file reader to parse the class file
+			IClassFileReader reader = new ClassFileReader(classFileBytes, IClassFileReader.CLASSFILE_ATTRIBUTES);
+
+			// Get the SourceFile attribute from the class file
+			ISourceAttribute sourceFileAttribute = reader.getSourceFileAttribute();
+			if (sourceFileAttribute == null) {
+				return null;
+			}
+
+			// Get the source file name from the constant pool
+			char[] sourceFileName = sourceFileAttribute.getSourceFileName();
+			if (sourceFileName == null || sourceFileName.length == 0) {
+				return null;
+			}
+
+			return new String(sourceFileName);
+		} catch (Exception e) {
+			JavaLanguageServerPlugin.logException("Error parsing class file format", e);
+		}
+		return null;
+	}
+}

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/handlers/ResolveSourceMappingHandler.java

@@ -19,18 +19,20 @@
 import org.apache.commons.lang3.StringUtils;
 
 public class ResolveSourceMappingHandler {
-    private static final Pattern SOURCE_PATTERN = Pattern.compile("([\\w$\\.]+\\/)?(([\\w$]+\\.)+[<\\w$>]+)\\(([\\w-$]+\\.java:\\d+)\\)");
+    private static final Pattern SOURCE_PATTERN = Pattern.compile(
+        "([\\w$\\.]+\\/)?(([\\w$]+\\.)+[<\\w$>]+)\\(([\\w-$]+\\.(?:java|kt|groovy|clj|scala)(?::\\d+)?)+\\)"
+    );
     private static final JdtSourceLookUpProvider sourceProvider = new JdtSourceLookUpProvider();
 
     /**
      * Given a line of stacktrace, resolve the uri of the source file or class file.
-     * 
+     *
      * @param lineText
      *              the line of the stacktrace.
      * @param projectNames
      *              A list of the project names that needs to search in. If the given list is empty,
      *              All the projects in the workspace will be searched.
-     * 
+     *
      * @return the uri of the associated source file or class file.
      */
     public static String resolveStackTraceLocation(String lineText, List<String> projectNames) {

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/managers/ContentProviderManager.java

@@ -14,6 +14,7 @@
 
 import java.net.URI;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 import java.util.regex.Pattern;
@@ -153,7 +154,7 @@ private List<ContentProviderDescriptor> findMatchingProviders(URI uri) {
 		Set<ContentProviderDescriptor> descriptors = getDescriptors(preferredProviderIds);
 		if (descriptors.isEmpty()) {
 			JavaLanguageServerPlugin.logError("No content providers found");
-			return null;
+			return Collections.emptyList();
 		}
 
 		String uriString = uri != null ? uri.toString() : null;
@@ -166,7 +167,7 @@ private List<ContentProviderDescriptor> findMatchingProviders(URI uri) {
 
 		if (matches.isEmpty()) {
 			JavaLanguageServerPlugin.logError("Unable to find content provider for URI " + uri);
-			return null;
+			return Collections.emptyList();
 		}
 
 		return matches;

org.eclipse.jdt.ls.tests/projects/maven/quickstart2/pom.xml

@@ -25,6 +25,16 @@
       <version>4.13</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>com.squareup.okhttp3</groupId>
+      <artifactId>okhttp-jvm</artifactId>
+      <version>5.3.2</version>
+    </dependency>
+    <dependency>
+      <groupId>com.typesafe.akka</groupId>
+      <artifactId>akka-actor_2.13</artifactId>
+      <version>2.8.8</version>
+    </dependency>
   </dependencies>
 
   <build>

org.eclipse.jdt.ls.tests/src/org/eclipse/jdt/ls/core/internal/commands/SourceAttachmentCommandTest.java

@@ -45,7 +45,7 @@
 import com.google.gson.Gson;
 
 public class SourceAttachmentCommandTest extends AbstractProjectsManagerBasedTest {
-	private static final String classFileUri = "jdt://contents/foo.jar/foo/bar.class?%3Dsource-attachment%2Ffoo.jar%3Cfoo%28bar.class";
+	private static final String classFileUri = "jdt://contents/foo.jar/foo/bar.java?%3Dsource-attachment%2Ffoo.jar%3Cfoo%28bar.class";
 	private IProject project;
 
 	@BeforeEach

org.eclipse.jdt.ls.tests/src/org/eclipse/jdt/ls/core/internal/handlers/CallHierarchyHandlerTest.java

@@ -189,8 +189,8 @@ public void outgoing_jar() throws Exception {
 
 		String jarUri = call0Calls.get(0).getTo().getUri();
 		assertTrue(jarUri.startsWith("jdt://"));
-		assertTrue(jarUri.contains("org.apache.commons.lang3.text"));
-		assertTrue(jarUri.contains("WordUtils.class"));
+		assertTrue(jarUri.contains("org.apache.commons.lang3.text/WordUtils.java?"));
+		assertTrue(jarUri.contains("org.apache.commons.lang3.text(WordUtils.class"));
 	}
 
 	@Test

org.eclipse.jdt.ls.tests/src/org/eclipse/jdt/ls/core/internal/handlers/ResolveSourceMappingHandlerTest.java

@@ -21,31 +21,45 @@
 
 public class ResolveSourceMappingHandlerTest extends AbstractProjectsManagerBasedTest {
 
-    @BeforeEach
+	@BeforeEach
 	public void setup() throws Exception {
 		importProjects("maven/quickstart2");
-    }
-
-    @Test
-    public void testResolveSourceUri() {
-        String uri = ResolveSourceMappingHandler.resolveStackTraceLocation("at quickstart.AppTest.shouldAnswerWithTrue(AppTest.java:10)", Arrays.asList("quickstart2"));
-        assertTrue(uri.startsWith("file://"));
-        assertTrue(uri.contains("quickstart2/src/test/java/quickstart/AppTest.java"));
-    }
-
-    @Test
-    public void testResolveDependencyUri() {
-        String uri = ResolveSourceMappingHandler.resolveStackTraceLocation("at org.junit.Assert.assertEquals(Assert.java:117)", Arrays.asList("quickstart2"));
-        assertTrue(uri.startsWith("jdt://contents/junit-4.13.jar/org.junit/Assert.class"));
+	}
+
+	@Test
+	public void testResolveSourceUri() {
+		String uri = ResolveSourceMappingHandler.resolveStackTraceLocation("at quickstart.AppTest.shouldAnswerWithTrue(AppTest.java:10)", Arrays.asList("quickstart2"));
+		assertTrue(uri.startsWith("file://"));
+		assertTrue(uri.contains("quickstart2/src/test/java/quickstart/AppTest.java"));
+	}
+
+	@Test
+	public void testResolveKotlinDerivedSources() {
+		String uri = ResolveSourceMappingHandler.resolveStackTraceLocation("at okhttp3.OkHttpClient.<init>(OkHttpClient.kt)", Arrays.asList("quickstart2"));
+		assertTrue(uri.startsWith("jdt://contents/okhttp-jvm-5.3.2.jar/okhttp3/OkHttpClient.kt"), "Unexpected URI: " + uri);
+		assertTrue(uri.contains("com%5C/squareup%5C/okhttp3%5C/okhttp-jvm%5C/5.3.2%5C/okhttp-jvm-5.3.2.jar"));
+	}
+
+	@Test
+	public void testResolveScalaDerivedSources() {
+		String uri = ResolveSourceMappingHandler.resolveStackTraceLocation("at akka.actor.Actor.$init$(Actor.scala:492)", Arrays.asList("quickstart2"));
+		assertTrue(uri.startsWith("jdt://contents/akka-actor_2.13-2.8.8.jar/akka.actor/Actor.scala"), "Unexpected URI: " + uri);
+		assertTrue(uri.contains("com%5C/typesafe%5C/akka%5C/akka-actor_2.13%5C/2.8.8%5C/akka-actor_2.13-2.8.8.jar"));
+	}
+
+	@Test
+	public void testResolveDependencyUri() {
+		String uri = ResolveSourceMappingHandler.resolveStackTraceLocation("at org.junit.Assert.assertEquals(Assert.java:117)", Arrays.asList("quickstart2"));
+		assertTrue(uri.startsWith("jdt://contents/junit-4.13.jar/org.junit/Assert.java"));
 		assertTrue(uri.contains(
 				"junit%5C/junit%5C/4.13%5C/junit-4.13.jar=/maven.pomderived=/true=/=/test=/true=/=/maven.groupId=/junit=/=/maven.artifactId=/junit=/=/maven.version=/4.13=/=/maven.scope=/test=/=/maven.pomderived=/true=/%3Corg.junit(Assert.class"));
-    }
+	}
 
-    @Test
-    public void testResolveDependencyUriWithoutGivingProjectNames() {
-        String uri = ResolveSourceMappingHandler.resolveStackTraceLocation("at org.junit.Assert.assertEquals(Assert.java:117)", null);
-        assertTrue(uri.startsWith("jdt://contents/junit-4.13.jar/org.junit/Assert.class"));
+	@Test
+	public void testResolveDependencyUriWithoutGivingProjectNames() {
+		String uri = ResolveSourceMappingHandler.resolveStackTraceLocation("at org.junit.Assert.assertEquals(Assert.java:117)", null);
+		assertTrue(uri.startsWith("jdt://contents/junit-4.13.jar/org.junit/Assert.java"));
 		assertTrue(uri.contains(
 				"junit%5C/4.13%5C/junit-4.13.jar=/maven.pomderived=/true=/=/test=/true=/=/maven.groupId=/junit=/=/maven.artifactId=/junit=/=/maven.version=/4.13=/=/maven.scope=/test=/=/maven.pomderived=/true=/%3Corg.junit(Assert.class"));
-    }
+	}
 }