[FLINK-29534] @TypeInfo on field requires field type to be valid Pojo

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Invalid
• Affects Version/s: 1.14.0, 1.15.0
• Component/s: API / Type Serialization System
• Assignee: Unassigned
• Reporter: Exidex
• Created: 07/Oct/22 10:19
• Updated: 07/Oct/22 11:38
• Resolved: 07/Oct/22 11:38

Description

The ability to place @TypeInfo on field was added in https://github.com/apache/flink/pull/8344 . But it seams like the fact that it requires field to be a valid POJO was overlooked. In my case I was trying to add custom serializer for Jackson's ObjectNode (wrapped in List but not sure if this is relevant https://issues.apache.org/jira/browse/FLINK-26470) which is not a valid POJO, and this requirement seams to defeat the whole purpose of such feature. It also doesn't look like like there's a way to register org.apache.flink.api.common.typeutils.TypeSerializer globally on 3rd-party types

code snippet from TypeExtractor:

Type fieldType = field.getGenericType();
if (!isValidPojoField(field, clazz, typeHierarchy) && clazz != Row.class) {
    LOG.info(
            "Class "
                    + clazz
                    + " cannot be used as a POJO type because not all fields are valid POJO fields, "
                    + "and must be processed as GenericType. {}",
            GENERIC_TYPE_DOC_HINT);
    return null;
}
try {
    final TypeInformation<?> typeInfo;
    List<Type> fieldTypeHierarchy = new ArrayList<>(typeHierarchy);
    TypeInfoFactory factory = getTypeInfoFactory(field);
    if (factory != null) {