@Override
  public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((stream == null) ? 0 : stream.hashCode());
    result = prime * result + ((system == null) ? 0 : system.hashCode());
    return result;
  }
Constructs a Samza stream object based upon an existing Samza stream.
@param other Reference to an already existing Samza stream.
samza-api/src/main/java/org/apache/samza/system/SystemStream.java