code: public Method getMethod(MethodIdentifier methodIdentifier) {
          final Map<ParamNameList, Map<String, Method>> nameMap = methodsByTypeName.get(methodIdentifier.getName());
          if (nameMap == null) {
              return null;
          }
          final Map<String, Method> paramsMap = nameMap.get(createParamNameList(methodIdentifier.getParameterTypes()));
          if (paramsMap == null) {
              return null;
          }
          return paramsMap.get(methodIdentifier.getReturnType());
      }
docs: Get a method declared on this object.
  
  @param methodIdentifier the method identifier
  @return the method, or {@code null} if no method of that description exists