Spring Data JPA - Query via Specification - ManyToMany and Join with Multiple Entities

Hello, I've assembled the following class Specification:

public class ItemVendedorSpecification implements Specification<ItemVendedor> {

    private static final long serialVersionUID = 1L;

    @Autowired
    CategoriaRepository categoriaRepository;

    @Autowired
    FabricanteRepository fabricanteRepository;

    @Autowired
    VendedorRepository vendedorRepository;

    private String descricao;

    private List<Long> categorias;
    private List<Long> fabricantes;
    private List<Long> vendedores;

    List<Predicate> predicates = new ArrayList<>();

    public ItemVendedorSpecification(String descricao, List<Long> categorias, List<Long> fabricantes, List<Long> vendedores) {
        super();
        this.descricao = descricao;
        this.categorias = categorias;
        this.fabricantes = fabricantes;
        this.vendedores = vendedores;
    }

    @Override
    public Predicate toPredicate(Root<ItemVendedor> root, CriteriaQuery<?> query, CriteriaBuilder builder) {

        if (!descricao.isEmpty()) {
            String PalavraChave[] = descricao.split(" ");
            for (String filtro : PalavraChave) {
                predicates.add(builder.like(builder.upper(root.get("id").get("produto").get("descricaoDetalhada")), "%" + filtro.toUpperCase() + "%"));
            }
        }

        predicates.add(builder.isTrue(root.get("disponivel")));

        if(!fabricantes.isEmpty()) {
            predicates.add(root.get("id").get("produto").get("fabricante").get("id").in(fabricantes));
        }

        if(!vendedores.isEmpty()) {
            predicates.add(root.get("id").get("vendedor").get("id").in(vendedores));

        }

        if(!categorias.isEmpty()) {
            predicates.add(root.join("id").get("produto").get("categorias").get("id").in(categorias));
        }

        return builder.and(predicates.toArray(new Predicate[1]));
    }
}

Almost all of the predicates are working, except the one that inserts the category criteria. It's not working and I'm having a hard time creating it.

In the way that it is returning the following error:

"Illegal attempt to dereference path source [null.produto.categorias] of basic type; nested exception is java.lang.IllegalStateException: Illegal attempt to dereference path source [null.produto.categorias] of basic type",

Can anyone help me in developing this if?

Below the detail of the ItemSeller class:

public class ItemVendedor implements Serializable{

    private static final long serialVersionUID = 1L;


    private ItemVendedorPK id = new ItemVendedorPK();
    private BigDecimal preco;
    private Boolean disponivel;
    private Date dt_insert;
    private Date dt_update;
    private BigDecimal desconto;

    public ItemVendedor() {

    }

    public ItemVendedor(Produto produto, Vendedor vendedor, BigDecimal preco, BigDecimal desconto ,Boolean disponivel) {
        super();
        this.id.setProduto(produto);
        this.id.setVendedor(vendedor);
        this.preco = preco;
        this.disponivel = disponivel;
        this.desconto = desconto;
    }

//GETs and SETs

As you can see, it has a field called id that is a key made up of the Vendedor vendedor and Produto produto fields.

Within the Product class I have a List<Categoria> categorias . Because a product can belong to several categories.

In turn, the Category class has id .

What I want to put in Specification , is a way to search all ItemVendedor that have within their list of categories some category that I quoted as a parameter in another list List<Long> categorias .

Personal, I am putting some more information to simplify understanding, below is a simplified class diagram to understand the context of the situation:

As you can see in the Product class a product can have several categories, and one category may have several products.

What I intend to do is the following: I want to give a list of values of type Long that refer to category codes. This parameter is passed through a list ( List<Long> categoriasId ) and will be used in the following query:

I want you to return all objects of type Vendor, where the list of product categories has at least 1 item that is within the last parameter list.

This approach is being done through Specification because it is a dynamic query, which will aggregate other criteria according to the class code.

Sincerely.