The `wait_for_metadata_version` parameter will instruct the cluster state
api to only return a cluster state until the metadata's version is equal or
greater than the version specified in `wait_for_metadata_version`. If
the specified `wait_for_timeout` has expired then a timed out response
is returned. (a response with no cluster state and wait for timed out flag set to true)
In the case metadata's version is equal or higher than `wait_for_metadata_version`
then the api will immediately return.
This feature is useful to avoid external components from constantly
polling the cluster state to whether somethings have changed in the
cluster state's metadata.
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