code: public String getCppReturnType(ClassModel classModel) {
          String type = processTemplate(cppReturnType, newHashMap("class", classModel));
          if (!type.isEmpty()) {
              return type;
          }
          return getCppType(classModel);
      }
docs: Process the <code>cppReturnType</code> template with the model
  <code>classModel</class> to obtain the C++ equivalent type to use
  as return type of functions and fields.
  
  @param classModel
  to model to use when processing the templates
  @return the template processing results