@Test
  public void extensionsWithImplementedOptions() {
    ExtensionWithImplementedOptions extension = new ExtensionWithImplementedOptions();

    // Ensure it's carried over to the AutoValue processor
    assertThat(new AutoValueProcessor(ImmutableList.of(extension)).getSupportedOptions())
        .contains(CUSTOM_OPTION);
  }
Tests that extensions providing their own implemented annotation types or options get picked
up.
value/src/test/java/com/google/auto/value/processor/ExtensionTest.java