code: public String toStringHierarchy(final TypeWriter typeWriter) {
          final StringBuilder res = new StringBuilder(types.size() * 50);
          writeHierarchy(root, "", "", res, typeWriter);
          return res.toString();
      }
docs: Write current root class hierarchy with resolved generics.
  Use custom writer to modify type rendering (on each line).
  
  @param typeWriter custom type writer
  @return current hierarchy with resolved generics