Doubt with HashSet

How could I use the following code with a HashSet?

This part of the code is used to assign a Manager to a worker, but I have a problem in the part that I mark with bold, because as I do it, it marks me as an error.

The Hashset I am using is: private HashSet<Empleado> empleados;

Original method with array:

for (int i = 0; i < empleados.length; i++) {
     if (empleados[i] instanceof Directivo && empleados[i].getDNI().equals(DNI_directivo)) {
            **d = (Directivo) empleados[i];**
      }
}

 e = new TrabajadorObra(d, DNI, nombre, cargo, nomina);

I try to do it this way for Hashset but I get an error.

for (Empleado e : empleados) {

     if (e instanceof Directivo && e.getDni().equals(dni4)){

           d = (Directivo) empleados;
      }

  e = new TrabajadorObra(d, DNI, nombre, cargo, nomina);