This commit changes the format of the `hits.total` in the search response to be an object with
a `value` and a `relation`. The `value` indicates the number of hits that match the query and the
`relation` indicates whether the number is accurate (in which case the relation is equals to `eq`)
or a lower bound of the total (in which case it is equals to `gte`).
This change also adds a parameter called `rest_total_hits_as_int` that can be used in the
search APIs to opt out from this change (retrieve the total hits as a number in the rest response).
Note that currently all search responses are accurate (`track_total_hits: true`) or they don't contain
`hits.total` (`track_total_hits: true`). We'll add a way to get a lower bound of the total hits in a
follow up (to allow numbers to be passed to `track_total_hits`).
Relates #33028
The contains syntax was added in #30874 but the skips were not properly
put in place.
The java runner has the feature so the tests will run as part of the
build, but language clients will be able to support it at their own
pace.
Suggestion responses were previously serialized as streamables which
made writing suggesters in plugins with custom suggestion response types
impossible. This commit makes them serialized as named writeables and
provides a facility for registering a reader for suggestion responses
when registering a suggester.
This also makes Suggestion responses abstract, requiring a suggester
implementation to provide its own types. Suggesters which do not need
anything additional to what is defined in Suggest.Suggestion should
provide a minimal subclass.
The existing plugin suggester integration tests are removed and
replaced with an equivalent implementation as an example
plugin.
Jim Ferenczi
Alpar Torok
Kazuhiro Sera
Andy Bristol