@Override
    public int compare(ENTITY first, ENTITY second) {
        final V f = get(first);
        final V 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);
    }
@param <ENTITY> the entity type
@param <D>      the database type
@param <V>      the field value type

@author  Per Minborg
@author  Emil Forslund

@since   2.2.0
runtime-parent/runtime-field/src/main/java/com/speedment/runtime/field/internal/ComparableFieldImpl.java