Merged pull request https://github.com/scylladb/scylla/pull/6551
from Juliusz Stasiewicz:
The command regenerates streams when:
generations corresponding to a gossiped timestamp cannot be
fetched from system_distributed table,
or when generation token ranges do not align with token metadata.
In such case the streams are regenerated and new timestamp is
gossiped around. The returned JSON is always empty, regardless of
whether streams needed regeneration or not.
Fixes#6498
Accompanied by: scylladb/scylla-jmx#109, scylladb/scylla-tools-java#172