code: protected final void defaultDispose() {
          if (getClassLoader() instanceof Closeable) {
              final Closeable cl = (Closeable) getClassLoader();
              Closeables.safeClose(cl);
          }
      }
docs: Default behavior for {@link #dispose()}: Calls {@link Closeable#close()
  close} if the Classloader returned by {@link #getClassLoader()} is an
  instance of {@link Closeable}.