books.add(new BookNested("Book #1", author1));
books.add(new BookNested("Book #2", author1));
books.add(new BookNested("Book #3", author2));
books.add(new BookNested("Book #4", author2));
LibraryNested library = new LibraryNested("Library #1", books);
MapperFactory factory = MappingUtil.getMapperFactory();
factory.registerClassMap(
factory.classMap(AuthorNested.class, AuthorDTO.class)
.field("name.fullName", "name").byDefault().toClassMap());