docs: protected static <K, V> void addOrRemoveProperty(Map<K, V> props, K key, V value)
      {
          if (value == null) {
              // Generic properties have already been added to the map.  Remove them
              // so they aren't confused with the builtin properties.
              props.remove(key);
          } else {
              props.put(key, value);
          }
      }