static boolean isGemfireObject(Object o) {
    return (o instanceof Function // fixes 43691
        || o.getClass().getName().startsWith("org.apache.geode."))
        && !(o instanceof PdxSerializerObject);
  }
Test to see if the object is in the gemfire package, to see if we should pass it on to a user's
custom serializater.
geode-core/src/main/java/org/apache/geode/internal/InternalDataSerializer.java