Memory leak when using tasks that use Worker API and process isolation

[big-guy]

Gradle can keep process-isolated workers across build invocations. The classpath, fork options and other details are kept about these processes.

When generating runtime classes for a Java process's fork options, Gradle generates hidden fields that contain references to the project state/service registry. Since these fork options are part of the information retained across builds, project state is also retained and never cleaned up.

This can eventually lead to OutOfMemory errors.

Expected Behavior

Gradle should not retain uncollectable project state across builds.

Current Behavior

Gradle inadvertently keeps project state across builds when a custom task uses the worker API and process isolation.

Context

This was introduced in 5.6