The PersonAddressValidator Constructor throws an exception when a null value is assigned to the argument.
That is different to the PersonNameValidator behaviour that does just log the error and avoids to throw an exception: https://github.com/openmrs/openmrs-core/blob/master/api/src/main/java/org/openmrs/validator/PersonNameValidator.java#L59
My assumptions would be that validators should deal in the same way with the null values. Hence the PersonAddressValidator should be coded in a way that avoids throwing exceptions.
Relates to: https://issues.openmrs.org/browse/TRUNK-5473