@Override
    public FindFromNullable<ENTITY, FK_ENTITY> nullableFinder(
            TableIdentifier<FK_ENTITY> identifier,
            Supplier<Stream<FK_ENTITY>> streamSupplier) {

        return new FindFromNullableReference<>(
            this, referenced, identifier, streamSupplier
        );
    }
@param <ENTITY>     the entity type
@param <D>          the database type
@param <V>          the field type
@param <FK_ENTITY>  the foreign entity type

@author  Emil Forslund
@author  Per Minborg

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