DataDependencyArc: simplified #hashCode() and #equals(Object)

    @Override

    public boolean equals(Object o) {

        if (this == o) {

            return true;

        }

        if (!(o instanceof DataDependencyArc)) {

            return false;

        }

        DataDependencyArc other = (DataDependencyArc) o;

        return Objects.equals(variable, other.variable)

                && Objects.equals(getSource(), other.getSource())

                && Objects.equals(getTarget(), other.getTarget());

        return super.equals(o) && Objects.equals(variable, ((DataDependencyArc) o).variable);

    }

    @Override

    public int hashCode() {

        return Objects.hash(variable, getSource(), getTarget());

        return Objects.hash(variable, super.hashCode());

    }

}