@Override
    public void releaseInstance(final ConstraintValidator<?, ?> instance) {
        if (!instance.getClass().getCanonicalName().startsWith("stroom.")) {
            // Not one of ours so pass to delegate
            delegate.releaseInstance(instance);
        }
        // A guice bound validator should go for garbage collection once all references are gone.
    }
Signals {@code ConstraintValidatorFactory} that the instance is no longer
being used by the Bean Validation provider.

@param instance validator being released
@since 1.1
stroom-util/src/main/java/stroom/util/validation/CustomConstraintValidatorFactory.java