build method
Implementation
ExecutionStep<T> build([T? context]) =>
ExecutionStep(root, context, history.build(),
transitions: transitions,
activeStates: activeStates.toSet()
..addAll(_statesToEnter) // includes default entry states
..removeAll(_statesToExit),
entryStates: _statesToEnter,
defaultEntryStates: _statesForDefaultEntry,
exitStates: _statesToExit,
defaultHistoryActions: _defaultHistoryActions);