@Override
    public Stream<FK_ENTITY> apply(ENTITY entity) {
        return stream().filter(
            getTargetField().equal(getSourceField().get(entity))
        );
    }
Default implementation of {@link FindFromNullable} for
{@link ReferenceField ReferenceFields}.

@author Emil Forslund
@since  3.0.11
runtime-parent/runtime-field/src/main/java/com/speedment/runtime/field/internal/method/FindFromNullableReference.java