@Size(min=10)
private Email email;

<?xml version="1.0" encoding="UTF-8"?>
<constraint-mappings
        xmlns="http://jboss.org/xml/ns/javax/validation/mapping"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://jboss.org/xml/ns/javax/validation/configuration validation-configuration-1.0.xsd">
           
    <constraint-definition annotation="javax.validation.constraint.Size">
        <validated-by include-existing-validators="true">
            <value>de.kba.zfer.core.util.beanvalidation.validator.SizeValidatorForStringDelegate</value>
        </validated-by>
    </constraint-definition>
   
</constraint-mappings>

package de.kba.zfer.core.util.beanvalidation.validator;

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import javax.validation.constraints.Size;

import de.kba.zfer.core.model.common.datatypes.FahrerlaubnisNummer;

public class SizeValidatorForStringDelegate implements ConstraintValidator<Size, FahrerlaubnisNummer> {

    private int min;

    private int max;

    @Override
    public void initialize(Size constraintAnnotation) {
        this.min = constraintAnnotation.min();
        this.max = constraintAnnotation.max();
        validateParameters();
    }

    @Override
    public boolean isValid(FahrerlaubnisNummer value, ConstraintValidatorContext context) {
        // sollte das gegebene StringDelegate-Object null sein, gib true zurueck
        if (value == null) {
            return true;
        }

        // ansonsten pruefe, ob die Laenge zwischen min und max liegt
        return value.length() >= min && value.length() <= max;
    }

    private void validateParameters() {
        if (min < 0) {
            throw new IllegalArgumentException("The min parameter cannot be negative.");
        }
        if (max < 0) {
            throw new IllegalArgumentException("The max parameter cannot be negative.");
        }
        if (max < min) {
            throw new IllegalArgumentException("The length cannot be negative.");
        }
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<validation-config xmlns="http://jboss.org/xml/ns/javax/validation/configuration"
                         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                         xsi:schemaLocation="http://jboss.org/xml/ns/javax/validation/configuration">
    ...
    <constraint-mapping>yourMappingFile.xml</constraint-mapping>
    ...
</validation-config>