This patch adds a config option to allow
configuring the cache_time for identity elements.
It is also including a complementary fix for
change I49e46e010c543f831959581b2122f59068f2c07b
that missed adjusting the correct template, and
used the wrong comparison "is not None".
Closes-bug: #2054418
Related-bug: #1771114
Change-Id: I57d376eb6c1f0f38cdd028aacf397aaf7f3a1cda