Enumerates potential issues with the underlying Pub/Sub
subscription configuration.
Values:
STATE_UNSPECIFIED (0):
The subscription configuration has not been
checked.
OK (1):
The Pub/Sub subscription is properly
configured.
SUBSCRIPTION_DELETED (2):
The subscription has been deleted.
TOPIC_DELETED (3):
The topic has been deleted.
SUBSCRIPTION_MISCONFIGURED (4):
Some of the subscription's field are
misconfigured.
