factory.registerClassMap(ClassMapBuilder.map(Book.class, BookMyDTO.class)
.field("title", "myTitle")
.field("author", "myAuthor")
.byDefault()
.toClassMap());
factory.build();
MapperFacade mapper = factory.getMapperFacade();
// BookChild, AuthorChild, LibraryChild don't directly
// implement Book, Author and Library