To close the loop. Also posted question to shiro-user list. No response...
but findings added there.

http://mail-archives.apache.org/mod_mbox/shiro-user/201801.mbox/%
3CCABYmcBhzv6ju8b%3D47AgfyPeP%3DEKhhCfrzhCqUggKY_%3Db-7zswg%
40mail.gmail.com%3E
secure ldap (over port 636).
actory</value>
protocol types of connections that may be pooled. Valid types are "plain"
and "ssl".
Ambari server.
calls per min) but there is some cost in establishing TLS connection.
connection to source LDAP?
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