@Override
    public final LongProperty longPropertyOf(String key, LongSupplier ifEmpty) {
        return numericPropertyOf(key, ifEmpty::getAsLong, NumericProperty::asLongProperty);
    }
{@inheritDoc}
@deprecated Not supported for observables
tool-parent/tool-config/src/main/java/com/speedment/tool/config/AbstractDocumentProperty.java