Hello,

I see that in the class "ElasticSearchIndex" in the method "pushMapping(String store, String key, KeyInformation information)" we ignore any custom properties from "KeyInformation information". 

As for me it is a drawback because we can't use specific features from ElasticSearch like on-disk index sorting, changing `similarity` algorithms for specific fields, using multi-fields and so on.

What do you think about adding a feature to allow custom properties?

I would appreciate if anyone could implement this feature. Is anyone interested?

If no one is able right now to implement this feature I can try to implement it.

Is there anything I should be aware of?

Best regards,

Alexandr