[Enhanced DynamoDb] List<CustomObject> is supported but not Set<CustomObject>?

[austinegri]

I found that a List for the DynamoDb enhanced client following works, but Set does not:

DynamoDbImmutable(builder = DdbObj.DdbObjBuilder.class)
public class DdbObj {
    @DynamoDbPartitionKey
    private final Integer id;
    private final List<CustomObject> objects;

DynamoDbImmutable(builder = CustomObject.CustomObjectBuilder.class)
public class CustomObject {
    private final Integer value;


TableSchema tableSchema = TableSchema.fromImmutableClass(DdbObj.class);

But the following does not:

DynamoDbImmutable(builder = DdbObj.DdbObjBuilder.class)
public class DdbObj {
    @DynamoDbPartitionKey
    private final Integer id;
    private final Set<CustomObject> objects;

TableSchema tableSchema = TableSchema.fromImmutableClass(DdbObj.class);

I get the error "IllegalStateException Converter not found for CustomObject"

After much time looking into the technical reason why this was it appears the root cause is that DDB Set attributes must be one of the following types: N, S, B see code.

If not for the above Set paramaterized type restriction to ImmutableTableSchema.java, It appears support for conversion for Set custom objects by adding the following:

            if (List.class.equals(rawType)) {
                EnhancedType<?> enhancedType = convertTypeToEnhancedType(parameterizedType.getActualTypeArguments()[0],
                                                                         metaTableSchemaCache, attributeConfiguration);
                return EnhancedType.listOf(enhancedType);
            }

            // *************** New Code Here ****************************
            if (Set.class.equals(rawType)) {
                EnhancedType<?> enhancedType = convertTypeToEnhancedType(parameterizedType.getActualTypeArguments()[0],
                                                                         metaTableSchemaCache, attributeConfiguration);
                return  EnhancedType.setOf(enhancedType);
            }
            // *************** New Code Ends Here ****************************

            if (Map.class.equals(rawType)) {
                EnhancedType<?> enhancedType = convertTypeToEnhancedType(parameterizedType.getActualTypeArguments()[1],
                                                                         metaTableSchemaCache, attributeConfiguration);
                return EnhancedType.mapOf(EnhancedType.of(parameterizedType.getActualTypeArguments()[0]),
                                          enhancedType);
            }

Note: did past search could not find info on set of custom objects. See similar 1, 2

My question is why can Set type not support collections of custom objects if they can be supported for Lists? Can we remove the Set type restriction and add the above changes to support Set?

[rufinoNL]

I checked this and got the same... If I translate all my Set's to List's, it's fine...