Gradle init script injection causes "Could not get unknown property 'com'" during project import (Gradle 9.2.0, Groovy 4)

[Missdrop]

Environment

• Extension: Gradle for Java (vscjava.vscode-gradle) 3.17.1 (server plugin bundled in extension)
• OS: macOS 15.5 (x86_64)
• Gradle: 9.2.0
• Groovy: 4.0.28
• Java: OpenJDK 21.0.9 (Zulu)
• Project: simple multi-project Java build with rootProject.name = 'CPT111-Group76' and subproject app

Summary

When the vscjava.vscode-gradle extension injects its init.gradle (which adds plugin-0.4.0.jar to the initscript classpath and then applies com.microsoft.java.bs.gradle.plugin.GradleBuildServerPlugin), Gradle fails during initialization with:

Could not get unknown property 'com' for root project 'CPT111-Group76' of type org.gradle.api.Project.

This prevents the Java Language Server from importing the workspace. Disabling the extension makes the project import successfully.

Reproduction steps

1. Open the Java project in VS Code with vscjava.vscode-gradle enabled.
2. The extension injects an init script located at <extension>/server/plugins/init.gradle with (simplified):

initscript {
  dependencies {
    classpath files('plugin-0.4.0.jar')
  }
}
allprojects {
  apply plugin: com.microsoft.java.bs.gradle.plugin.GradleBuildServerPlugin
}

3. The VS Code Java Language Server / Gradle tooling client fails to import build targets and logs the MissingPropertyException.

Observed logs

• Excerpt from the language server / extension logs:

[Error] Initialization failed
java.util.concurrent.CompletionException: ... Could not get unknown property 'com' for root project 'CPT111-Group76' of type org.gradle.api.Project.
Caused by: groovy.lang.MissingPropertyException: Could not get unknown property 'com' for root project 'CPT111-Group76' of type org.gradle.api.Project.
  at init_...(/.../init.gradle:8)

• Running from terminal with the extension init script reproduces the same error:

./gradlew --init-script /.../init.gradle tasks --stacktrace
FAILURE: Build failed with an exception.
* Where:
Initialization script '/.../init.gradle' line: 8
* What went wrong:
Could not get unknown property 'com' for root project 'CPT111-Group76' of type org.gradle.api.Project.

Notes about attempts to workaround

• I tried creating a plugin-0.4.0.jar file in the project root (and also a symlink pointing to the extension's plugin-0.4.0.jar) so that initscript { classpath files('plugin-0.4.0.jar') } can find the jar. The jar is present and contains com.microsoft.java.bs.gradle.plugin.GradleBuildServerPlugin, but the init script still throws the MissingPropertyException when evaluating the apply plugin: com.microsoft... line. It appears Groovy may parse the bare class reference before the class is available in the classloader, causing com to be treated as an unknown property of the Project object.

Why this is likely a classloading/parse-time issue

• The error indicates Groovy tried to resolve com as a property on the Project (MissingPropertyException) instead of recognizing it as a package/class reference, which suggests the plugin class wasn't resolvable at that parse time or that the script evaluation order makes the bare reference unsafe.
• Different Gradle/Groovy versions can change script parsing/classloading timing. In my environment (Gradle 9.2.0, Groovy 4.0.28) the injected script fails to apply the plugin using the bare class reference.

Suggested fixes / mitigation options

1. Use safe plugin application in init.gradle:
   • After adding classpath, attempt to load the class via classloader and apply via project.plugins.apply(pluginClass), wrapped in try/catch. Example:

initscript {
  dependencies {
    classpath files('plugin-0.4.0.jar')
  }
}
allprojects {
  try {
    def pluginClass = this.class.classLoader.loadClass('com.microsoft.java.bs.gradle.plugin.GradleBuildServerPlugin')
    project.getPlugins().apply(pluginClass)
  } catch (Throwable t) {
    // Log and continue without failing the build initialization
  }
}

2. If the plugin is or can be published with a plugin id, prefer applying by id (string) instead of a bare class reference:

apply plugin: 'com.microsoft.java.bs.gradle.plugin' // if published as plugin id

3. Add defensive checks in the injected init script to avoid throwing during project configuration time; if a class can't be loaded, skip applying the plugin and log a clear warning.

4. Document the compatibility matrix for injected init scripts vs Gradle/Groovy versions and provide a toggle for users to opt-out of init script injection.

Request

• Please consider changing the injected init.gradle to apply the plugin in a way that won't throw MissingPropertyException during Gradle initialization (see suggested code above).
• If you need further logs, I can attach the full client.log and the terminal stacktrace output.

Local environment summary (collected):

• Gradle 9.2.0 (Launcher JVM: 21.0.9)
• Groovy 4.0.28
• Java: OpenJDK 21.0.9 (Zulu)
• OS: macOS 15.5 x86_64
• Extension version tested: vscjava.vscode-gradle 3.17.1

[github-actions]

Hi @Missdrop, 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.

Suggested Workarounds

• Modify the injected init.gradle to avoid bare class references before the JAR is on the classpath:

  initscript {
    dependencies {
      classpath files('plugin-0.4.0.jar')
    }
  }
  allprojects {
    try {
      def pluginClass = this.class.classLoader.loadClass(
        'com.microsoft.java.bs.gradle.plugin.GradleBuildServerPlugin'
      )
      project.plugins.apply(pluginClass)
    } catch (Throwable t) {
      logger.warn("Could not apply GradleBuildServerPlugin, skipping: $t")
    }
  }

• If the plugin is published with an ID, apply by string ID instead:

  allprojects {
    apply plugin: 'com.microsoft.java.bs.gradle.plugin'
  }

• As an alternative, include the plugin JAR in buildSrc so it’s visible to all scripts (see below).

High-Confidence Reference

• Classloader isolation for script plugins may require putting dependencies in buildSrc:
  • Fails on class import in included sript for custom repositoty #1286 (comment)

Other references with low confidence

Click to expand

• Title: Could not get unknown property (eclipse-jdt.ls [error] [gradle-server] Gradle version is required #922)
  • Similar MissingPropertyException, but for settings.gradle properties rather than init script class loading
  • Could not get unknown property eclipse-jdtls/eclipse.jdt.ls#922

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!

[chagong]

Hi @Missdrop the suggested mitigation change looks safe. But I want to know why it hits such error, can you lower your groovy version to 4.0.16 to see if error persists?

[Missdrop]

Hi @Missdrop the suggested mitigation change looks safe. But I want to know why it hits such error, can you lower your groovy version to 4.0.16 to see if error persists?

Recently I found, this issue can be solved by change the plugin into developing version. So it's not a problem anymore.