Return a Datum int-map value holding the elements supplied to pushBack or append sorted by their keys.
The caller is responsible for releasing the resources of the returned Datum object. Calling this method indicates that the caller is finished building the Datum int-map and no further values shall be appended. The behavior is undefined if any method of this object, other than its destructor, is called after sortAndCommit invocation.
Datum int-map holding the sorted elements supplied to this builder