@Override
    public void fromData(DataInput din,
        DeserializationContext context) throws IOException, ClassNotFoundException {
      super.fromData(din, context);
      relayRecipient = DataSerializer.readObject(din);
      processorId = din.readInt();
      processorType = din.readInt();
      allRegions = din.readBoolean();
      if (!allRegions) {
        regionPath = DataSerializer.readString(din);
      }
    }
returns a set of all DistributedRegions for allRegions processing
geode-core/src/main/java/org/apache/geode/internal/cache/StateFlushOperation.java