Describes the current state of the execution. More states
might be added in the future.
Values:
STATE_UNSPECIFIED (0):
Invalid state.
ACTIVE (1):
The execution is in progress.
SUCCEEDED (2):
The execution finished successfully.
FAILED (3):
The execution failed with an error.
CANCELLED (4):
The execution was stopped intentionally.
UNAVAILABLE (5):
Execution data is unavailable. See the state_error
field.
QUEUED (6):
Request has been placed in the backlog for
processing at a later time.
