@Override public Object getKey(Object message) { return joinFn.getFirstKey(message); }
@Override public Object getKey(Object message) { return joinFn.getFirstKey(message); }
@Override public Object getKey(Object message) { return joinFn.getFirstKey(message); }
@Override public Object getKey(Object message) { return joinFn.getFirstKey(message); }
@Override public Object getKey(Object message) { return joinFn.getFirstKey(message); }