The vast majority of method and variable naming has already been made Database independent with OPT-7244. However there are two DTOs that contain fields that have ES in their name. Their renaming is not trivial because it also requires an operation during upgrade. 

The field in question is 

esTypeIndexRefersTo

It is present in TimestampBasedImportIndexDto and PositionBasedImportIndexDto.

1. This field should be promoted to ImportIndexDto (which both Dtos above inherit from). 
2. It needs to be renamed to dbTypeIndexRefersTo
3. This renaming needs to be considered in the migration for each of the indexes using it, since the renaming will affect the database
4. Tests for the upgrade steps need to be adapted (if applicable)