Use validation inside validator or dont validate empty string with another validation or change empty string to null

Question

Having request body as:

"pesel": "",
"something": "BLABLABLA"

I would like to achieve logic as below:

1. If the field is null or is an empty string, then field isValid
2. If the fields lenght is more than 0 then use @PESEL validation

I have tried adding JsonInclude adnotation but it didnt help, @PESEL adnotation throw error with empty string - "":

@JsonInclude(JsonInclude.Include.NON_EMPTY)
@PESEL
private String pesel;

Creating own validator:

 @Component
public class PeselCustomValidator implements ConstraintValidator<PESELCustom, String> {
    @PESEL
    private String pesel;
    @Override
    public boolean isValid(String pesel, ConstraintValidatorContext constraintValidatorContext) {
if(pesel.equals("")){return true;}
// Many variations like @PESEL in the parameters
// @Valid etc
    }
}

Unfortunately nothing is working as expected.

On the other hand I have also tried with validation order and some way to change "" to null in the initBinder but without success. Thank you in advance!