According to https://github.com/ehcache/ehcache2 

Ehcache 2.x is approaching End of Life.

Ehcache 3.0 was released April 2016.

As of October 2022, this project will receive reduced attention, excepting for important/critical fixes.

After September 2023, we will no longer maintain Ehcache 2.x.

Jira DC currently use the ehcache below version.

<spring.security.version>5.5.7</spring.security.version>
        <ehcache.version>2.10.2-atlassian-18</ehcache.version>
        <datacenter-filestore.version>0.8.9</datacenter-filestore.version> 

Since Ehcache 3.x has been out for years, we should start using it.