Values:
UNSPECIFIED (0):
An internal checker should never be in the
unspecified state.
CREATING (1):
The checker is being created, provisioned, and configured. A
checker in this state can be returned by
ListInternalCheckers or GetInternalChecker, as well
as by examining the long running
Operation <https://cloud.google.com/apis/design/design_patterns#long_running_operations>
that created it.
RUNNING (2):
The checker is running and available for use. A checker in
this state can be returned by ListInternalCheckers or
GetInternalChecker as well as by examining the long
running
Operation <https://cloud.google.com/apis/design/design_patterns#long_running_operations>
that created it. If a checker is being torn down, it is
neither visible nor usable, so there is no "deleting" or
"down" state.
