I need to list content entities in their original languages, but views module shows all content translations.
I need something like grouping by entity IDs.
I think the proper filter is the following:
"Content: Default translation (= True)"
I achieved the desired result by adding the Translation source (= Not specified)
filter.
The original entity translations have the Translation source
field empty. And it's pretty safe to use the Not specified
language because entities using it are untranslatable.