public Optional<Boolean> optionalOldSelf() {
        return Optional.ofNullable(this.optionalOldSelf);
    }
@return optionalOldSelf is used to opt a transition rule into evaluation even when the object is first created, or if the old object is missing the value.

When enabled `oldSelf` will be a CEL optional whose value will be `None` if there is no old value, or when the object is initially created.

You may check for presence of oldSelf using `oldSelf.hasValue()` and unwrap it after checking using `oldSelf.value()`. Check the CEL documentation for Optional types for more information: https://pkg.go.dev/github.com/google/cel-go/cel#OptionalTypes

May not be set unless `oldSelf` is used in `rule`.
sdk/java/src/main/java/com/pulumi/kubernetes/apiextensions/v1/outputs/ValidationRulePatch.java