code: public Method getMethod(Class<?> returnType, String name, Class<?>... paramTypes) {
          final Map<ParamList, Map<Class<?>, Method>> nameMap = methods.get(name);
          if (nameMap == null) {
              return null;
          }
          final Map<Class<?>, Method> paramsMap = nameMap.get(createParamList(paramTypes));
          if (paramsMap == null) {
              return null;
          }
          return paramsMap.get(returnType);
      }
docs: Get a method declared on this object.
  
  @param returnType the method return type
  @param name       the name of the method
  @param paramTypes the parameter types of the method
  @return the method, or {@code null} if no method of that description exists