LambdaRecordWindow implements RecordWindow { @Override public Collection<String> getChannelIdentifiers() { return getChannelIdentifiers.get(); } LambdaRecordWindow(
            SerializableFunction<MRecord, Boolean> inWindowLambda,
            SerializableResultFunction<ArrayList<String>> getChannelIdentifiers
    ); @Override boolean inWindow(MRecord record); @Override Collection<String> getChannelIdentifiers();  }
@Test public void getChannelIdentifiers() { assertTrue(window.getChannelIdentifiers().contains("test")); assertTrue(clone.getChannelIdentifiers().contains("test")); }