Thanks to the new XContent abstraction, CamelCase are back. All JSON
requests now support also CamelCase fields (such in the query DSL), and
responses can be sent back in CamelCase fields with the addition of the
case HTTP parameter (actually REST parameter) set to
The main idea here is to support using DSLs in dynamic languages (such as
Groovy) that use CamelCase as their naming convention. So, if you are using
Groovy, for example, the query DSL can include "constantScore" as a query,
on top of "constant_score".
Note, this does not apply to the actual indexable source. The same JSON
indexed will be returned, with the original casing.