anchor.diff:  NOTE: The type name must match the `<protobuf package>.<protobuf message>` exactly!
   +
   .AuthorMarshaller.java
  +[source,java]
   ----
   public class AuthorMarshaller implements MessageMarshaller<Author> {
   
  
positive.code: ----
  
  .Book.java
  ----
  public class Book {
     private final String title;
  
negative.code: some additional steps that are detailed here. Let's say we have the following user classes:
  
  .Author.java
  [source,java]
  ----
  public class Author {
     private final String name;
  