@Override
    public int compare(ENTITY first, ENTITY second) {
        final E f = get(first);
        final E s = get(second);
        if (f == null && s == null) return 0;
        else if (f == null) return 1;
        else if (s == null) return -1;
        else return f.compareTo(s);
    }
Default implementation of the {@link EnumForeignKeyField}-interface.

@author Emil Forslund
@since  3.0.10
runtime-parent/runtime-field/src/main/java/com/speedment/runtime/field/internal/EnumForeignKeyFieldImpl.java