Validation Constraints with nested objects in play2.0

ChildParameter.java

import play.data.validation.Constraints;
import java.util.List;

public class ChildParameter {

    @Constraints.Required
    public List<String> idChildList;

    @Constraints.Required
    @Constraints.Max(2)
    @Constraints.Min(0)
    public Integer type;

    public ChildParameter() {
    }

}

ParentParameter.java

import play.data.validation.Constraints;
import javax.validation.Valid;
import java.util.List;

public class ParentParameter {

    @Constraints.Required
    public String id;

    @Valid
    @Constraints.Required
    public List<ChildParameter> childs;

    public ParentParameter() {
    }

}