@Override
    public void toData(DataOutput out,
        SerializationContext context) throws IOException {
      super.toData(out, context);
      out.writeInt(processorId);
    }
Processes this message. This method is invoked by the receiver of the message.

@param dm the distribution manager that is processing the message.
geode-core/src/main/java/org/apache/geode/internal/cache/partitioned/InterestEventMessage.java