Project dependencies don't invalidate properly in the configuration cache

I’m using the Wire Gradle plugin and the Gradle configuration cache.

My Wire build includes this syntax:

  sourcePath {
    srcProject(":upstream-protos")
    include("file_a.proto")
    include("file_b.proto")
  }

Unfortunately when I make changes to upstream-protos my Wire project doesn’t rebuild enough, and produces an incorrect compilation result.

In the interim I’m using this to workaround:

    tasks.withType<WireTask> {
      notCompatibleWithConfigurationCache("Project dependencies don't invalidate properly")
    }

I can also use --no-configuration-cache as a workaround, but that’s more severe.

Start by reproducing the configuration-cache behavior with the Wire Gradle plugin, the sourcePath block, and the upstream-protos project described here. Trace how WireTask records the project dependency and compare builds with and without configuration cache. Done means changes in upstream-protos invalidate the relevant Wire work and prevent stale compilation results without requiring the workaround.