1. Create a new content type with a single text field.
2. Create a new content (name: "A") of the new content type.
3. Add a new taxonomy entry assignment field to the new content type using the "Tags" taxonomy.
4. Check the Solr Document of content "A". The new field does not exist yet.
5. Run ibexa:reindex --content-ids=<content id of "A">.
6. Check the Solr Document of content "A". It now has a tags_is_empty_b: true field.
7. Edit the content "A" without changing anything and publish the new version.
8. Check the Solr Document of content "A". The value of tags_is_empty_b is now false, even though the value of …_tags_count_i is 0.

Note
The reason for this problem is probably the implementation of \Ibexa\Taxonomy\FieldType\TaxonomyEntryAssignment\Type::isEmptyValue() which checks if \Ibexa\Taxonomy\FieldType\TaxonomyEntryAssignment\Value::$taxonomy is null. In the steps above, it is null after the Solr reindex, but got the correct tags value after editing the content.
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