docs: @JRubyMethod
      public static IRubyObject add_type(IRubyObject self, IRubyObject taguri, IRubyObject cls) {
          IRubyObject tags = self.callMethod(self.getRuntime().getCurrentContext(), "tags");
          ((RubyHash)tags).fastASet(taguri, cls);
          return self.getRuntime().getNil();
      }