Spring annotation validation and indexing for nested objects

Question

In Spring MVC, I have annotated my parent Dto and list of child Dto's with bean-validation annotations as below:

class ParentDto {
  @NotBlank
  private String parentName;
  @Valid
  private Set<ChildDto> childList;
  //getter and setter
}

class ChildDto {
  @NotBlank
  private String childName;
  //getter and setter
}

If childName is empty in one of the child objects then spring returns error message as below without the index of child object:

[{"errorCode":"NotNull","field":"parentDto.childList[].childDto ","message":"may not be null"}]

How can I enable spring to return a message with index (telling which child has problem) something like below:

[{"errorCode":"NotNull","field":"parentDto.childList[1].childDto ","message":"may not be null"}]

Answer 1

I figured out why index was missing from the error message. Since i was using Set instead of List for the collection of child objects therefore it was not able to index it. Once change to list it works fine.