We're removing support for @IndexedEmbedded.indexNullAs in HSEARCH-2465.
As a result, users are no longer able to search for documents that have an object field present/missing.
We should support the concept of "exists" queries for object fields, or at least nested fields.
Note: there are Search 5 tests that should pass when this ticket is resolved, and that are currently disabled in the pom.xml of the Elasticsearch module. Those tests will be (or have been) outlined as part of HSEARCH-2390.
Also, some relevant tests are disabled using the ElasticsearchSupportInProgress category.
Agreed, the "exists" query of ES seems a better solution to the problem. We should actually investigate and see if we can do the same within our Lucene backend: our approch based on null-tokens was necessary when we introduced it, but apparently it looks like that nowadays there are better solutions for this.