@Test
  public void testExtensibility() throws Exception {
    setupSerializer(new BigIntegerAutoSerializer(true,
        "org.apache.geode.pdx.AutoSerializableJUnitTest.BigHolder"), false);

    doExtensible("with autoSerializer handling Big*");
  }
A serializable with a writeReplace method should use standard serialization.
geode-core/src/integrationTest/java/org/apache/geode/pdx/AutoSerializableJUnitTest.java