Compatibility with ElasticSearch v6.x and 7.x

[davin4u]

In this article it is said
https://www.elastic.co/guide/en/elasticsearch/reference/6.x/removal-of-types.html ES team is going to remove types at all. It is possible to have only one type inside the index starting from v6.x. Also they suggest to use "_doc" as the type name for the future compatibility with v7.x where types will be removed.
How would you suggest to use the plugin in the project right now to make possible to use ES v6.x to reduce "risks" for future updates?

[coffeeburrito]

I override getTypeName() on the model to return "_doc", but apparently an empty string works as well (see #169).

[coffeeburrito]

(Edit: this was in response to a now-deleted comment) The "_doc" type wasn't introduced until 6.2.0, so you probably need to upgrade your cluster. elastic/elasticsearch#27816