code: static String typeArgumentsString(DocEnv env, ClassType cl, boolean full) {
          if (env.legacyDoclet || cl.getTypeArguments().isEmpty()) {
              return "";
          }
          StringBuilder s = new StringBuilder();
          for (Type t : cl.getTypeArguments()) {
              s.append(s.length() == 0 ? "<" : ", ");
              s.append(getTypeString(env, t, full));
          }
          s.append(">");
          return s.toString();
      }
docs: Return the actual type arguments of a parameterized type as an
  angle-bracketed string.  Class name are qualified if "full" is true.
  Return "" if there are no type arguments or we're hiding generics.