Ok, so in the meantime one solution for using java with the elasticsearch search API, could be to use the Java API library for structuring queries and aggregations and then serialize to json string with the org.elasticsearch.common.xcontent.XContentHelper class. But I am still wondering why in the java api doc I can find only the org.elasticsearch.client maven dependency and nowhere the dependency for org.elasticsearch.
Reading this doc one could think that the Java API is usable only with the transport client, which is not totally true..
Francesco