@Override
  public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
    fromData(in, InternalDataSerializer.createDeserializationContext(in));
  }
Abstract class for subclasses that want to be Externalizable in addition to being
DataSerializableFixedID.
<p>
Note: subclasses must also provide a zero-arg constructor

@since GemFire 5.7
geode-core/src/main/java/org/apache/geode/internal/ExternalizableDSFID.java