@Override
  protected void appendFields(StringBuilder buff) {
    super.appendFields(buff);
    buff.append("; key=").append(getKey());
    buff.append("; op=").append(op);

    if (eventId != null) {
      buff.append("; eventId=").append(eventId);
    }
    if (versionTag != null) {
      buff.append("; version=").append(versionTag);
    }
  }
Assists the toString method in reporting the contents of this message

@see PartitionMessage#toString()
geode-core/src/main/java/org/apache/geode/internal/cache/partitioned/PRUpdateEntryVersionMessage.java