DataTransferObject ExampleDTO {
  Map<String, @AnotherDTO> keyToValue;
}

leads to error markers in editor as well as generation error: mismatched input 'Map' expecting '}'

I have seen https://fornax.itemis.de/jira/browse/CSC-250 but a DTO is not stored in DB, so there is no reason to not support Maps inside DataTransferObjects.