Predicate to find collection that contains a value

Question

I have an entity that has an collection of String:

@Entity
class A {
    @Column
    private Set<String> coll;
}

The sql to create the table is the following:

create table a (
  coll varchar(10)[]
);

In the database, I have one column containing the array in the form of {myString1, myString2}.

I'm trying to create a Predicate/Specification to find the entities whose collection coll contains a specific value. I can't find how to do it.

I've tried stuff like:

public Specification<A> filter(String val) {
    return (root, query, builder) -> {
        builder.isMember(val, root.get("coll"))
    };
}

But it's not working. I've seen people mentionning joins with root.join("coll"), but it's not working either, probbaly because it's not a OneToMany relation, I have nothing to join on, I just have an array of String.

Any idea?

Thanks in advance!