code: public static String getMethodDescriptor(
          final Type returnType,
          final Type[] argumentTypes)
      {
          StringBuffer buf = new StringBuffer();
          buf.append('(');
          for (int i = 0; i < argumentTypes.length; ++i) {
              argumentTypes[i].getDescriptor(buf);
          }
          buf.append(')');
          returnType.getDescriptor(buf);
          return buf.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.