Christoph Büscher 5f9dfe3186 Add parsing from xContent to InternalSearchHit and InternalSearchHits (#22429)
This adds methods to parse InternalSearchHit and InternalSearchHits from their
xContent representation. Most of the information in the original object is
preserved when rendering the object to xContent and then parsing it back.
However, some pieces of information are lost which we currently cannot parse
back from the rest response, most notably:

* the "match" property of the lucene explanation is not rendered in the
  "_explain" section and cannot be reconstructed on the client side
* the original "shard" information (SearchShardTarget) is only rendered if the
  "explanation" is also set, also we loose the indexUUID of the contained
  ShardId because we don't write it out. As a replacement we can use
  ClusterState.UNKNOWN_UUID on the receiving side
2017-01-10 14:00:04 +01:00
..