prod code. It's disabled automatically for "test code"
                     (which is good: our tests have intentional violations), but
                     Error Prone doesn't know it's building test code unless we
                     pass -XepCompilingTestOnlyCode, and that argument needs to
                     be passed as part of the same <arg> as -Xplugin:ErrorProne,

            <sourceFileExclude>**/ForceGuavaCompilation*</sourceFileExclude>
          </sourceFileExcludes>
          <!-- The above exclusion doesn't actually matter unless I prevent Javadoc from autodiscovering the source in the sourcepath, which defaults to the source directory :\ Boo for -sourcepath. -->
          <sourcepath>doesnotexist</sourcepath>