Bean Validation on Nested Fields doesn't work

[kamaydeo]

I'm trying to use ConstrainedFields for Bean Validation but unable to get it to work.

<restdocs-api-spec.version>0.9.9</restdocs-api-spec.version>
<restdocs-spec.version>0.18</restdocs-spec.version>

As you can see below, CreateBookRequestDto has property 'author' and it should not be null.

@Value
@Builder
public class CreateBookRequestDto {
    @NotEmpty String title;
    @NotNull @Valid AuthorDto author;
}

@Value
@Builder
@Validated
public class AuthorDto {
    @NotEmpty String firstName;
    @NotEmpty String lastName;
}

@Test
    public void create() throws Exception {
        //when
        BookDto book = BookDto.builder().isbn("0-9705-6867-3").title("A Time To Kill").author(AuthorDto.builder().firstName("John").lastName("Grisham").build()).build();
        CreateBookRequestDto createBookRequestDto = CreateBookRequestDto.builder().title("A Time To Kill").author(AuthorDto.builder().firstName("John").lastName("Grisham").build()).build();
        when(bookService.create(any())).thenReturn(book);
        //then
        ConstrainedFields constrainedFields = new ConstrainedFields(CreateBookRequestDto.class);
        mvc
                .perform(post("/books")
                            .content(new ObjectMapper().writeValueAsBytes(createBookRequestDto))
                            .contentType(APPLICATION_JSON_VALUE)
                            .accept(APPLICATION_JSON_VALUE))
                .andExpect(status().isOk())
                .andDo(print())
                .andDo(
                        document(
                                "create-book",
                                resourceDetails().description("Create a book."),
                                requestFields(
                                        constrainedFields.withPath("title").description("The title of the book."),
                                        constrainedFields.withPath("author").description("The Author of the book."),
                                        constrainedFields.withMappedPath("author.firstName", "author").description("The author's first name."),
                                        constrainedFields.withMappedPath("author.lastName", "author").description("The author's last name.")
                                ),
                                responseFields(
                                        fieldWithPath("isbn").description("The ISBN of the book."),
                                        fieldWithPath("title").description("The title of the book."),
                                        fieldWithPath("author.firstName").description("The author's first name."),
                                        fieldWithPath("author.lastName").description("The author's last name.")
                                )
                        )
                );
    }

Generated openapi-3.0.yml file. As you can see below, author should be required but it doesn't show up in the required fields.

components:
  schemas:
    books-1095758460:
      required:
      - title
      type: object
      properties:
        author:
          required:
          - firstName
          - lastName
          type: object
          properties:
            lastName:
              type: string
              description: The author's last name.
            firstName:
              type: string
              description: The author's first name.
          description: The Author of the book.
        title:
          minLength: 1
          type: string
          description: The title of the book.

Is it a bug or am I missing something?

[kamaydeo]

Just in case if it's a bug, I created an issue on restdocs-api-spec. [https://github.com/ePages-de/restdocs-api-spec/issues/138]