This commit adds support for version and version_type to the Term Vectors API.
This could be useful in the following case whereby the user gets a document
and later wants to generate its TVs. With version, this would ensure that only
the TVs of that particular document are generated, and error out if the
document has been updated in between.
Closes#7480
By default term vectors are now realtime, as opposed to previously near
realtime. If they are not found in the index, they will be generated on the
fly. The document is fetched from the transaction log and treated as an
artificial document. One can set `realtime` parameter to `false` in order to
disable this functionality. This consequently makes the MLT query realtime in
fetching documents, as it previsouly used to be before switching from using
the multi get API to the mtv API.
Closes#7846