Values:
STATE_UNSPECIFIED (0):
Default value. This value is unused.
CREATING (1):
This is an initialization state. During this
stage, the resources such as Pub/Sub topics are
allocated for the AgentPool.
CREATED (2):
Determines that the AgentPool is created for
use. At this state, Agents can join the
AgentPool and participate in the transfer jobs
in that pool.
DELETING (3):
Determines that the AgentPool deletion has
been initiated, and all the resources are
scheduled to be cleaned up and freed.