* Returns before-state of top level container. Implementations are encouraged,
* but not required to provide this state.
*
- * @param root Class representing data container
* @return State of object before modification. Null if subtree was not present,
* or the implementation cannot provide the state.
*/
/**
* Returns after-state of top level container.
*
- * @param root Class representing data container
* @return State of object after modification. Null if subtree is not present.
*/
@Nullable T getDataAfter();