[FLINK-13159] Fix incorrect subclass serializer reconfiguration in Po…

…joSerializer

flink-core/src/main/java/org/apache/flink/api/java/typeutils/runtime/PojoSerializerSnapshot.java

@@ -474,13 +474,21 @@ private static Tuple2<LinkedHashMap<Class<?>, Integer>, TypeSerializer<Object>[]
  Iterator<TypeSerializer<?>> serializersForPreexistingRegistrations =
  Arrays.asList(preExistingRegistrationsCompatibility.getNestedSerializers()).iterator();
 
- for (Map.Entry<Class<?>, TypeSerializer<?>> registration : newSubclassRegistrations.entrySet()) {
- // new registrations should simply be appended to the subclass serializer registry with their new serializers;
- // preexisting registrations should use the compatibility-checked serializer
- TypeSerializer<?> newRegistration = (reconfiguredSubclassSerializerRegistry.containsKey(registration.getKey()))
- ? serializersForPreexistingRegistrations.next()
- : registration.getValue();
- reconfiguredSubclassSerializerRegistry.put(registration.getKey(), newRegistration);
+ // first, replace all restored serializers of subclasses that co-exist in
+ // the previous and new registrations, with the compatibility-checked serializers
+ for (Map.Entry<Class<?>, TypeSerializer<?>> oldRegistration : reconfiguredSubclassSerializerRegistry.entrySet()) {
+ if (newSubclassRegistrations.containsKey(oldRegistration.getKey())) {
+ oldRegistration.setValue(serializersForPreexistingRegistrations.next());
+ }
+ }
+
+ // then, for all new registration that did not exist before, append it to the registry simply with their
+ // new serializers
+ for (Map.Entry<Class<?>, TypeSerializer<?>> newRegistration : newSubclassRegistrations.entrySet()) {
+ TypeSerializer<?> oldRegistration = reconfiguredSubclassSerializerRegistry.get(newRegistration.getKey());
+ if (oldRegistration == null) {
+ reconfiguredSubclassSerializerRegistry.put(newRegistration.getKey(), newRegistration.getValue());
+ }
  }
 
  return decomposeSubclassSerializerRegistry(reconfiguredSubclassSerializerRegistry);