boolean allEndOfStream() {
    return eosStates.values().stream().allMatch(EndOfStreamState::isEndOfStream);
  }
Update the state upon receiving an end-of-stream message.
@param eos message of {@link EndOfStreamMessage}
@param ssp system stream partition
samza-core/src/main/java/org/apache/samza/operators/impl/EndOfStreamStates.java