JPA Embeddeble PK and nullable field

I have a table called "Attributes" which has a PK of 3 fields which can be null. In this case Style_no is not null but item_no and size_no are null.

Is it possible to have a Embeddeble PK where fields can be null?

@Entity@Table(name="ATTRIBUTE")public class Attribute {    @EmbeddedId    private AttributePK attrPK;    ...    @Embeddable    public static class AttributePK implements Serializable{        private static final long serialVersionUID = -2976341677484364274L;        @Column(name="STYLE_NO", nullable=true)        protected String styleNo;        @Column(name="ITEM_NO", nullable=true)        protected String itemNo;        @Column(name="SIZE_NO", nullable=true)        protected String sizeNo;    ...

When i try to reference over one field e.g. style_no the result amount is 0.

@OneToMany(fetch=FetchType.LAZY, cascade=CascadeType.ALL, orphanRemoval=true, mappedBy="attrPK.styleNo")@MapKey(name="attrPK.name")public Map<String,Attribute> attributesX;

OR

@OneToMany(fetch=FetchType.LAZY, cascade=CascadeType.ALL, orphanRemoval=true)@JoinColumn(name="STYLE_NO", referencedColumnName="STYLE_NO")private List<Attribute> attributes;

When i remove item_no and size_no as pk im receiving a valid result.

Edit: To make my question more specific. Is per JPA guideline or "common sense" not allowed to use nullable fields for EmbeddebedId? If not, what annotions or logic do i need to add to make it work without adding another PK?Once filling the nullable field in the PK with values. The result is corrct.

Thank you very much!