code: public static Object getObjectValue(Map<String, Object> yamlObject, String key, boolean allowsEmpty)
              throws YamlConvertException {
          if (yamlObject == null) {
              throw new NullPointerException();
          }
          Object obj = yamlObject.get(key);
          if (obj == null && !yamlObject.containsKey(key) && !allowsEmpty) {
              throw new YamlConvertException(String.format(MSG_KEY_NOT_FOUND, key));
          }
          return obj;
      }
docs: (null may mean null value for the specified key)