read / write
The evaluation behavior of this constraint in the absense of 'Policy'. Possible string values are:
- "CONSTRAINT_DEFAULT_UNSPECIFIED" : This is only used for distinguishing unset values and should never be used.
- "ALLOW" : Indicate that all values are allowed for list constraints. Indicate that enforcement is off for boolean constraints.
- "DENY" : Indicate that all values are denied for list constraints. Indicate that enforcement is on for boolean constraints.