The execution state of this task.

PENDING_EXECUTION Task is waiting for its precondition tasks to finish to start the execution.
IN_PROCESS Task is under processing.
SUCCEED Task execution successfully finished. There's no more change after this state.
FAILED Task execution failed. There's no more change after this state.
FATAL Task execution failed and cause the whole event execution to fail immediately. There's no more change after this state.
RETRY_ON_HOLD Task execution failed and waiting for retry.
SKIPPED Task execution skipped. This happens when its precondition wasn't met, or the event execution been canceled before reach to the task. There's no more changes after this state.
CANCELED Task execution canceled when in progress. This happens when event execution been canceled or any other task fall in fatal state.
PENDING_ROLLBACK Task is waiting for its dependency tasks' rollback to finish to start its rollback.
ROLLBACK_IN_PROCESS Task is rolling back.
ROLLEDBACK Task is rolled back. This is the state we will set regardless of rollback succeeding or failing.
SUSPENDED Task is a SuspensionTask which has executed once, creating a pending suspension.