Currently, when an object is mapped with subobjects: false, trying to ingest a document that has nested objects leads to a mapping exception.

In a couple of occasions, we've been talking about that it would be convenient if Elasticsearch could automatically flatten the fields instead of the client having to know about the subobjects setting. This would make subobjects: false more of a drop-in replacement that allows for a much easier adoption, without changes in the client.

Note that the _source should ideally stay untouched, just the stored fields should be flattened automatically.

Some related issues

• Support metrics with dots in their names apm#347
• Better default mappings for logs #88777
• Add support for subobjects: false package-spec#349