Elasticsearch inner hits in java api

I am trying to implement inner hits with elasticsearch using Java API, but I cannot find much of any documentation on it or examples that other people are using. I have my JSON search that works as follows:

{
  "query": {
    "filtered": {
      "query": {
        "match_all": {}
      },
      "filter": {
        "nested": {
          "path": "locations",
          "filter": {
            "geo_distance": {
              "distance": "20km",
              "locations.address.geoLocation": {
                "lat": 38.07061,
                "lon": -76.77514
              }
            }
          },
          "inner_hits": {}
        }
      }
    }
  }
}

I see an InnerHitsBuilder and addInnerHit methods in the elasticsearch library but I cannot find the documentation on how to use them.

Note that there are plenty of test cases in the ES source code where each feature is being tested, so browsing the ES code is a incredibly rich source of information. Inner hits makes no exception and you can find all inner_hits test cases in the InnerHitsTests.java class.

So your query above can be created like this:

    // build the geo_distance filter
    GeoDistanceFilterBuilder geo = FilterBuilders
            .geoDistanceFilter("locations.address.geoLocation")
            .distance("20km")
            .lat(38.07061)
            .lon(-76.77514);

    // build the nested filter and add inner_hits
    NestedFilterBuilder nested = FilterBuilders
           .nestedFilter("locations", geo)
           .innerHit(new QueryInnerHitBuilder());  <--- this is what you're looking for

    // wrap it all inside a filtered query
    FilteredQueryBuilder query = QueryBuilders
           .filteredQuery(QueryBuilders.matchAllQuery(), nested);