Hello,
I am trying to add a NOSQL data into my JPA-based application, following this tutorial.
The entity I want to add, was befored modeled without NOSQL in this way:

Triple.java

Code:
@Entity
    @IdClass(ConceptPk.class)
    @Table(name = "triple")
    public class TripleDBModel {
    	protected List<Annotation> annotations;
    	public Concept conceptUriSubject;
    	public Concept conceptUriObject;
    	public Concept conceptUriPredicate;

    	@ManyToMany(
    	        cascade={CascadeType.ALL },	
    	        fetch=FetchType.LAZY
    	)	
        @JoinTable(name = "triple_has_annotation", 
        		joinColumns={@JoinColumn(name="uri_concept_subject"), @JoinColumn(name="uri_concept_object"), @JoinColumn(name="uri_concept_predicate") },  		
        		inverseJoinColumns=@JoinColumn(name="annotation_id") )
        public List<Annotation> getAnnotations() {
    		return annotations;
    	}
    	public void setAnnotations(List<Annotation> annotations) {
    		this.annotations = annotations;
    	}
ConceptPk.java

Code:
 @Embeddable
    public class ConceptPk implements java.io.Serializable {
    
    	private static final long serialVersionUID = 1L;
    	public Concept conceptUriSubject;
    	public Concept conceptUriObject;
    	public Concept conceptUriPredicate;
    
    	@Id 
    	@ManyToOne(cascade=CascadeType.MERGE)
    	@JoinColumn(name="uri_concept_subject")
    	public Concept getConceptUriSubject() {
    		return conceptUriSubject;
    	}
    	public void setConceptUriSubject(Concept conceptUriSubject) {
    		this.conceptUriSubject = conceptUriSubject;
    	}
I am omiting repetitions, but the 3 `Concept`s are part of the primary key, of the @Id.
Adapting this entity to NOSQL:

Code:
@Entity
    @IdClass(ConceptPk.class)
    @Table(name = "triple")
    @NodeEntity(partial = true)
    public class TripleDBModel {
    //Fields referring other entities shouldn't be initialized
    	protected List<Annotation> annotations;
    	//public Concept conceptUriSubject;
    	//public Concept conceptUriObject;
    	//public Concept conceptUriPredicate;
    
    	
    	@RelatedTo(type = "conceptUriSubject", elementClass = Concept.class)
        Set<Concept> conceptUriSubject;
Now the question, which actually are two questions:

A) `@RelatedTo(type = "conceptUriSubject", elementClass = Concept.class)` gives me error on Eclipse, and advises me to add a cast, but this doesn't solve the error. I don't know if I must an annotation or any other additional thing to `Class.java`

B) As I have specified, the primery key is composed by 3 concepts, and `ConceptPK.java` is required. JPA modelling is ok, but I don't know how to do the same in NOSQL