code: public LanguageVersion languageVersion() {
          try {
              Object retVal;
              String methodName = "languageVersion";
              Class<?>[] paramTypes = new Class<?>[0];
              Object[] params = new Object[0];
              try {
                  retVal = invoke(methodName, JAVA_1_1, paramTypes, params);
              } catch (DocletInvokeException exc) {
                  return JAVA_1_1;
              }
              if (retVal instanceof LanguageVersion) {
                  return (LanguageVersion)retVal;
              } else {
                  messager.error(Messager.NOPOS, "main.must_return_languageversion",
                                 docletClassName, methodName);
                  return JAVA_1_1;
              }
          } catch (NoClassDefFoundError ex) { // for boostrapping, no Enum class.
              return null;
          }
      }
docs: Return the language version supported by this doclet.
  If the method does not exist in the doclet, assume version 1.1.