Specifies the default behavior in the absence of any policy for the
constraint. This must not be CONSTRAINT_DEFAULT_UNSPECIFIED.
Immutable after creation.
Values:
CONSTRAINT_DEFAULT_UNSPECIFIED (0):
This is only used for distinguishing unset
values and should never be used.
ALLOW (1):
Indicate that all values are allowed for list
constraints. Indicate that enforcement is off
for boolean constraints.
DENY (2):
Indicate that all values are denied for list
constraints. Indicate that enforcement is on for
boolean constraints.