code: public static String getMethodDescriptor(final Type returnType, final Type... argumentTypes) {
      StringBuilder stringBuilder = new StringBuilder();
      stringBuilder.append('(');
      for (int i = 0; i < argumentTypes.length; ++i) {
        argumentTypes[i].appendDescriptor(stringBuilder);
      }
      stringBuilder.append(')');
      returnType.appendDescriptor(stringBuilder);
      return stringBuilder.toString();
    }
docs: Returns the descriptor corresponding to the given argument and return types.
  
  @param returnType the return type of the method.
  @param argumentTypes the argument types of the method.
  @return the descriptor corresponding to the given argument and return types.