When having VS Code open on a project that has a generated code srcDir, and running gradle commands from the command-line in that same folder, lock contention issues cause corrupted artifacts

Expected Behavior

I'm using VS Code 1.17.2 + vscode-java 0.12.0, gradle 4.2.1 to build a Java 8 SpringBoot application om macOS 10.12.6. The build uses an xjc ant task to generate .java files from a few .xsd documents in the resources directory. I've verified that in my case, 11 ObjectFactory.java files are generated, and consequently, 11 ObjectFactory.class files are compiled correctly. I would expect all of those class files to end up in my resulting .war artifact.

Current Behavior

A random number of ObjectFactory.class files end up in the .war file. To verify this, see how to reproduce below.

Context

The issue occurs when vscode is open on a project which contains a generated code folder, specified as a srcDir entry in the build.gradle, and a terminal on the same project is used to run gradle commands. It looks like gradle from the command-line is competing with vscode-java/eclipse-jdt-ls/buildship for locks on files.

Note that it has been observed that specifying options.fork in the compileJava {..} section also works around the problem, although I suspect that only happens due to timing (i.e, think this is a race condition/lock contention of sorts).

Steps to Reproduce

1. Git clone reproducer (git clone git@github.com:rubin55/reproducer.git)
2. Open reproducer as folder in vscode
3. Let vscode initialize, open a few Java files to see that class lookup works
4. In particular, open a .java file from the generated source folder
5. Open a terminal and cd to the reproducer
6. Run this, a few times in a row:

gradle clean build && echo I found $(unzip -l build/libs/*.war | grep ObjectFactory.class | wc -l) ObjectFactory objects in archive while $(find build/classes/ -type f -name ObjectFactory.class | wc -l) were compiled and $(find build/generated/ -type f -name ObjectFactory.java | wc -l) java files where generated

Example output:

I found 1 ObjectFactory objects in archive while 11 were compiled and 11 java files where generated

7. If the issue manifests, you will see that the resultant .war file will have missing ObjectFactory.class files (see message above).
8. Observe vscode-java .log file and see backtraces that coincide with this issue. See attached vscode-java.log.

Your Environment

VS Code 1.17.2
VS Code Java 0.12.0
Gradle 4.2.1
Java 8 r144
macOS 10.12.6

Comienza con el repositorio de reproducción, su build.gradle y el directorio de código fuente generado descrito en el informe. Ejecuta repetidamente el comando gradle clean build mientras VS Code y vscode-java están abiertos, y compara los archivos Java generados, las clases compiladas y el contenido del WAR; inspecciona el vscode-java.log adjunto en busca de los backtraces correspondientes. Se considera completado cuando el build reproducido incluye de forma consistente todos los archivos ObjectFactory.class generados.