as reported on the user list...
We encounter a lot of log warning entries from the MetricsHistoryHandler saying
o.a.s.h.a.MetricsHistoryHandler Unknown format of leader id, skipping:
I don't even know what this MetricsHistoryHandler does, but at least there's a warning.
Looking at the code you can see that it has to fail if the hostname of the node contains a hyphen: