public int hashCode() {
    if (hashCode == 0) {
      final int prime = 31;
      int result = 1;
      result = prime * result + hashCodeMemberId(membershipID);
      result = prime * result + (int) (sequenceID ^ (sequenceID >>> 32));
      result = prime * result + (int) (threadID ^ (threadID >>> 32));
      hashCode = result;
    }
    return hashCode;
  }
form the hashcode for the memberID byte array
geode-core/src/main/java/org/apache/geode/internal/cache/EventID.java