@Entity
public class ChildEntity {
    private Long id;
    private String name;
    private ParentEntity parent;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column( name = "ID" )
    public ID getId() { return this.id; }

    public void setId( ID id ) { this.id = id; }

    @Column( name = "NAME", nullable = false, length = 50 )
    public String getName() { return this.name; }

    public void setName( String name ) { this.name = name; }

    @ManyToOne
    @JoinColumn( name = "PARENT_ID", nullable = false )
    public ParentEntity getParent() { return this.parent; }

    public void setParent( ParentEntity parent ) { this.parent = parent; }

}

@Entity
public class ParentEntity {
    private Long id;
    private String name;
    private Set<ChildEntity> childs = new HashSet<ChildEntity>();

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column( name = "ID" )
    public ID getId() { return this.id; }

    public void setId( ID id ) { this.id = id; }

    @Column( name = "NAME", nullable = false, length = 50 )
    public String getName() { return this.name; }

    public void setName( String name ) { this.name = name; }

    @OneToMany( mappedBy = "parent", cascade = { CascadeType.ALL } )
    public Set<ChildEntity> getChilds() { return this.childs; }

    public void setChilds( Set<ChildEntity> childs ) { this.childs = childs; }

}

...

EntityManager entityManager = this.entityManagerFactory.createEntityManager();

ManagedType< ? > managedTypePE = entityManager.getMetamodel().entity( ParentEntity.class );
Attribute<?, ?> attrPEChilds = managedTypePE.getAttribute( "childs" );
Assert.assertTrue( attrPEChilds.isCollection() ); // its OK

ManagedType< ? > managedTypeCE = entityManager.getMetamodel().entity( ChildEntity.class );
Attribute<?, ?> attrCEParent = managedTypeCE.getAttribute( "parent" ); // <<== it will be a SingularAttribute
Assert.assertTrue( attrCEParent.isAssociation() ); // <<== THIS WILL FAIL!!!

...