SpecBuilder

public class ItemSpecificationBuilder {

    //uzycie w CustomItemRepositoryImpl

    private List<Specification<Item>> specs;

    {
        specs = new ArrayList<>();
    }

    public ItemSpecificationBuilder withNameLike(String name) {
        if (name == null || name.trim().equals("")) return this;
        specs.add(
                (root, criteriaQuery, criteriaBuilder) ->
                        criteriaBuilder.like(root.get("name"), "%" + name + "%")
        );
        return this;
    }

    public ItemSpecificationBuilder withDescriptionLike(String description) {
        if (description == null) return this;
        specs.add(
                (root, criteriaQuery, criteriaBuilder) ->
                        criteriaBuilder.like(root.get("description"), "%" + description + "%")
        );
        return this;
    }

    public ItemSpecificationBuilder withCategoriesIdsIn(Collection<Long> categoriesIds) {
        if (categoriesIds == null || categoriesIds.isEmpty()) return this;
        specs.add(
                (root, criteriaQuery, criteriaBuilder) ->
                        criteriaBuilder.and(root.join("categories").get("id").in(categoriesIds))
        );
        return this;
    }

    public Specification<Item> build() {
        if (specs.isEmpty()) {
            return null;
        } else {
            Iterator<Specification<Item>> iterator = specs.iterator();
            Specification<Item> finalSpecification = iterator.next();
            while (iterator.hasNext()) {
                finalSpecification = Specifications.where(finalSpecification).and(iterator.next());
            }
            return finalSpecification;
        }
    }
}