code: public static File getCacheDirectory( File classesDirectory )
      {
          String classesDirectoryName = classesDirectory.getName();
          String cacheDirectoryName = classesDirectoryName.replace( TEST_CLASSES, CACHE ).replace( CLASSES, CACHE );
          return new File( classesDirectory.getParentFile(), cacheDirectoryName );
      }
docs: Returns directory for incremental compilation cache files.
  
  @param classesDirectory compilation output directory
  @return directory for incremental compilation cache files