Return value of "org.gradle.api.tasks.SourceSet.getCompileClasspath()" is null

[graetzer]

Extension Name: vscode-gradle
Extension Version: 3.17.1
OS Version: MacOS 15.7.3 (24G419)
VSCode version: 1.107.1

Describe the bug

We have a large propriatery gradle project, with many different sub-modules. I am unable to open it with this plugin, due to the following exceptions in the java language server.
An error I see regulary is Cannot invoke "org.gradle.api.file.FileCollection.getFiles()" because the return value of "org.gradle.api.tasks.SourceSet.getCompileClasspath()" is null

[Error - 13:00:22] 02.01.2026, 13:00:22 Initialization failed 
java.util.concurrent.CompletionException: org.eclipse.lsp4j.jsonrpc.ResponseErrorException: Cannot invoke "org.gradle.api.file.FileCollection.getFiles()" because the return value of "org.gradle.api.tasks.SourceSet.getCompileClasspath()" is null
	at java.base/java.util.concurrent.CompletableFuture.reportJoin(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture.join(Unknown Source)
	at com.microsoft.gradle.bs.importer.Utils.getBuildTargetsMappedByProjectPath(Utils.java:55)
	at com.microsoft.gradle.bs.importer.GradleBuildServerProjectImporter.importProjects(GradleBuildServerProjectImporter.java:324)
	at com.microsoft.gradle.bs.importer.GradleBuildServerProjectImporter.importToWorkspace(GradleBuildServerProjectImporter.java:228)
	at org.eclipse.jdt.ls.core.internal.managers.ProjectsManager.importProjects(ProjectsManager.java:164)
	at org.eclipse.jdt.ls.core.internal.managers.ProjectsManager.initializeProjects(ProjectsManager.java:126)
	at org.eclipse.jdt.ls.core.internal.handlers.InitHandler$1.runInWorkspace(InitHandler.java:263)
	at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:43)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)
Caused by: org.eclipse.lsp4j.jsonrpc.ResponseErrorException: Cannot invoke "org.gradle.api.file.FileCollection.getFiles()" because the return value of "org.gradle.api.tasks.SourceSet.getCompileClasspath()" is null
	at org.eclipse.lsp4j.jsonrpc.RemoteEndpoint.handleResponse(RemoteEndpoint.java:220)
	at org.eclipse.lsp4j.jsonrpc.RemoteEndpoint.consume(RemoteEndpoint.java:204)
	at org.eclipse.lsp4j.jsonrpc.json.StreamMessageProducer.handleMessage(StreamMessageProducer.java:185)
	at org.eclipse.lsp4j.jsonrpc.json.StreamMessageProducer.listen(StreamMessageProducer.java:97)
	at org.eclipse.lsp4j.jsonrpc.json.ConcurrentMessageProcessor.run(ConcurrentMessageProcessor.java:114)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
	at java.base/java.util.concurrent.FutureTask.run(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.base/java.lang.Thread.run(Unknown Source)

[Error - 13:00:23] 02.01.2026, 13:00:23 _/pack/replication/dbms/main/src/com/complexible/stardog/pack/replication [in stardog_2dae651b] does not exist
Java Model Exception: Error in Java Model (code 969): _/pack/replication/dbms/main/src/com/complexible/stardog/pack/replication [in stardog_2dae651b] does not exist
	at org.eclipse.jdt.internal.core.JavaElement.newNotPresentException(JavaElement.java:548)
	at org.eclipse.jdt.internal.core.PackageFragmentRoot.getUnderlyingResource(PackageFragmentRoot.java:768)
	at org.eclipse.jdt.internal.core.PackageFragment.getUnderlyingResource(PackageFragment.java:417)
	at org.eclipse.jdt.internal.core.Openable.getUnderlyingResource(Openable.java:333)
	at org.eclipse.jdt.internal.core.CompilationUnit.getUnderlyingResource(CompilationUnit.java:1095)
	at org.eclipse.jdt.ls.core.internal.handlers.BaseDiagnosticsHandler.collectNonJavaProblems(BaseDiagnosticsHandler.java:198)
	at org.eclipse.jdt.ls.core.internal.handlers.BaseDiagnosticsHandler.endReporting(BaseDiagnosticsHandler.java:149)
	at org.eclipse.jdt.internal.core.ReconcileWorkingCopyOperation.reportProblems(ReconcileWorkingCopyOperation.java:157)
	at org.eclipse.jdt.internal.core.ReconcileWorkingCopyOperation.executeOperation(ReconcileWorkingCopyOperation.java:126)
	at org.eclipse.jdt.internal.core.JavaModelOperation.run(JavaModelOperation.java:751)
	at org.eclipse.jdt.internal.core.JavaModelOperation.runOperation(JavaModelOperation.java:816)
	at org.eclipse.jdt.internal.core.CompilationUnit.reconcile(CompilationUnit.java:1431)
	at org.eclipse.jdt.ls.core.internal.handlers.BaseDocumentLifeCycleHandler.publishDiagnostics(BaseDocumentLifeCycleHandler.java:338)
	at org.eclipse.jdt.ls.core.internal.handlers.BaseDocumentLifeCycleHandler.publishDiagnostics(BaseDocumentLifeCycleHandler.java:301)
	at org.eclipse.jdt.ls.core.internal.handlers.BaseDocumentLifeCycleHandler$PublishDiagnosticJob.run(BaseDocumentLifeCycleHandler.java:798)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

To Reproduce

Unsure what the exact issue is with out project, I can't give a minimal example

Expected behavior

Project classpath to be set correctly in java extension

Output from "Gradle for Java"

[info] Found 16706 tasks
[error] [gradle-server] Could not execute build using connection to Gradle distribution 'https://services.gradle.org/distributions/gradle-8.11-bin.zip'.
[error] Error running build: build: Could not execute build using connection to Gradle distribution 'https://services.gradle.org/distributions/gradle-8.11-bin.zip'.
[info] Java Home: /Users/simon/.vscode/extensions/redhat.java-1.50.0-darwin-arm64/jre/21.0.9-macosx-aarch64
[info] JVM Args: -XX:+HeapDumpOnOutOfMemoryError,-Xmx4096m,-Dfile.encoding=UTF-8,-Duser.country=DE,-Duser.language=de,-Duser.variant
[info] Gradle User Home: /Users/simon/.gradle
[info] Gradle Version: 8.11
[info] > Configure project :starrocks
bazel_cmd args: [bazel, build]
bazel_cmd args: [bazel, test]

> Configure project :
zookeeperVersion=3.8.5
curatorVersion=5.5.0
curatorTestVersion=5.3.0
version=12.0.0-SNAPSHOT-20260102
releaseDate=04 Jun 2025
Initial OS: macosx
Building on OS: macosx, aarch64, 15.7.3
ronn not found, setting to default: /usr/local/bin/ronn

> Configure project :starrocks:main:native
Building with JDK: /Users/simon/.vscode/extensions/redhat.java-1.50.0-darwin-arm64/jre/21.0.9-macosx-aarch64
Java version: 21
Building on OS: macosx, aarch64, 15.7.3
[Incubating] Problems report is available at: file:///Users/simon/stardog/build/reports/problems/problems-report.html

Deprecated Gradle features were used in this build, making it incompatible with Gradle 9.0.

You can use '--warning-mode all' to show the individual deprecation warnings and determine if they come from your own scripts or plugins.

For more on this, please refer to https://docs.gradle.org/8.11/userguide/command_line_interface.html#sec:command_line_warnings in the Gradle documentation.

CONFIGURE SUCCESSFUL in 32s
[info] Found 16706 tasks

Does the bug still exist if you disable all other extensions?
Yes

[github-actions]

Hi @graetzer, I'm an AI Support assistant here to help with your issue. While the team reviews your request, I wanted to provide some possible tips and documentation that might help you in the meantime.

No relevant references found in the provided sources.

Suggestions:

• Ensure every subproject that defines Java code applies the java plugin so that sourceSets.compileClasspath is never null.
• Upgrade to the latest “Gradle for Java” and “Gradle” extensions in VS Code, and use the matching Gradle Wrapper (e.g. 8.11).
• If the problem persists, please open a new issue against the Gradle extension: https://github.com/microsoft/vscode-gradle/issues. Provide a minimal reproducible project, your build.gradle or settings.gradle, and the exact stack trace.

The team will respond to your issue shortly. I hope these suggestions are helpful in the meantime. If this comment helped you, please give it a 👍. If the suggestion was not helpful or incorrect, please give it a 👎. Your feedback helps us improve!

[graetzer]

I tried applying the java-library plugin to each sub-module; but that did not change anything

[chagong]

@graetzer are you able to share your repo?

[graetzer]

No unfortunately not, I can't share the code base. The issue seems to go away if I disable the gradle build server. The output of the build server is equivalent. Is there a way to add the --info flag to the build server ?

The supplied build action failed with an exception.

FAILURE: Build failed with an exception.

* What went wrong:
Multiple build operations failed.
    Cannot invoke "org.gradle.api.file.FileCollection.getFiles()" because the return value of "org.gradle.api.tasks.SourceSet.getCompileClasspath()" is null
    Cannot invoke "org.gradle.api.file.FileCollection.getFiles()" because the return value of "org.gradle.api.tasks.SourceSet.getCompileClasspath()" is null
> Cannot invoke "org.gradle.api.file.FileCollection.getFiles()" because the return value of "org.gradle.api.tasks.SourceSet.getCompileClasspath()" is null
> Cannot invoke "org.gradle.api.file.FileCollection.getFiles()" because the return value of "org.gradle.api.tasks.SourceSet.getCompileClasspath()" is null

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.

CONFIGURE FAILED in 15s