translateSort in JacksonMappingAwareSortTranslator returns unsorted for fields on another model

[WARciech]

RepositoryRestController does not accept sorting for fields which it does not understand.

In previous versions of Spring even if a field didn't exist in the model which is being exposed by RepositoryRestController/BasePathAwareController it was still working, for example when model looked like that:

public class Model {
  private String field;
}

and you asked for anotherField (which does not exist on the backend, but might exist in database for example after executing aggregation in MongoDB)

public class SecondModel {
  private String anotherField;
}

Spring was properly mapping sorting to this field.

From version 2.6, this is being overridden in class JacksonMappingAwareSortTranslator and when calling translateSort() for a field that comes from another model, it returns unsorted.