Error: addAll(Collection<? extends IKlant) in Vector cannot be applied to (Vector<DbObject>)

IntelliJ gives an error where Eclipse does not.
When I run the program, it works perfectly fine.

A little bit of info:

Our application has objects that will be fetched from a database. These objects have the `DbObject` interface.

We have two types of Klant (= customer) objects. I'll take `TBCKlantImpl` as an example.

We'll use a method to fetch data from the database. Due to legacy, we'll use Vectors
The method's signature:

public <E extends DbObject, T extends E> Vector<E> getTableObjects(Class<T> c, String where_clause);

I can use it like this:

Vector<IKlant> custs = new Vector<IKlant>();
Vector<IBCKlant> customers = DbVarHolder.get().getTableObjects(TBCKlantImpl.class, "WHERE 1=1 LIMIT 4");
custs.addAll(customers);

No errors here.

But when I use it like this:

Vector<IKlant> custs = new Vector<IKlant>();
custs.addAll(DbVarHolder.get().getTableObjects(TBCKlantImpl.class, "WHERE 1=1 LIMIT 4, 4"));

Now I get an error message.

But the program runs fine with the Eclipse compiler.

Has anyone else experienced this?
Were you able to solve it?
If so, how?