Updating class references (generated classes from proto files)

Hi. I'm using Protocol Buffers in my Java application. I'm using Gradle, and the protobuf-gradle-plugin to generate Java classes from the .proto files. The generated proto Java files are added to my sourceSet in build.gradle.

plugins {
    id 'java'
    id 'application'
    id "com.google.protobuf" version "0.8.12"
}

repositories {
    jcenter()
}

dependencies {
    implementation 'com.google.guava:guava:28.2-jre'
    testImplementation 'junit:junit:4.12'
}

application {
    mainClassName = 'test.gradle.project.proto.App'
}

sourceSets {
  main {
    java {
      srcDirs 'src/main/java'
      srcDirs 'build/generated/source/proto/main/java'
    }
  }
}

compileJava.dependsOn 'generateProto'

Whenever I make a change to the proto files, and re-generate the proto Java classes via ./gradlew generateProto, the language server does not update the references, and I get errors in the editor. AFAIK there's two ways to update the class references:

1. Restart vscode, or
2. Run "Update project configuration" from the grade build file

Neither options are ideal, and option 2 can sometimes take a long time to complete on large projects. I would think updating class references should be a quick process. No compilation is necessary, the language server just needs to update it's reference cache (or something along those lines).

Would it be possible to

1. Provide a new command to update class references?
2. Watch the build directory/sourceSets and automatically update references when generated files change?

I'm also developing a gradle vscode extension, and from my extension i would potentially be able to provide a list of generated class files to the vscode-java extension via an API call, so that could also be a potential option.

Looking for any ideas/suggestions/changes to make this process more user friendly and fast.

Environment

• Operating System: MacOS catalina
• JDK version: openjdk 11.0.2
• Visual Studio Code version: 1.45.1
• Java extension version: 0.62.0

Steps To Reproduce

1. Clone this repo: https://github.com/badsyntax/test-gradle-project-proto
2. Open test-gradle-project-proto in vscode
3. Open src/main/java/test/gradle/project/proto/App.java
4. Note classes for Greeting don't exist
5. In the vscode terminal, run ./gradlew generateProto
6. Note references for Greeting still don't exist
7. Either restart vscode, or run "Update project configuration" from build.gradle
8. Note references for Greeting now exist and there's no errors in the editor

Keep in mind this is a very small project and you won't see the performance issues I mentioned above, but does demonstrate the extension not updating references when files on disk change.

Reproduce the issue with the linked test-gradle-project-proto repository, using build.gradle and src/main/java/test/gradle/project/proto/App.java. Run ./gradlew generateProto after opening the project and observe whether Greeting references update without restarting VS Code or running Update project configuration. Done means generated class references refresh after files change, without requiring a full project configuration update.