Drop support for embedding EhCache 3 until it supports Jakarta EE 9

[wilkinsona]

ehcache/ehcache3#2946

[linghengqian]

Not sure if this should be answered here. But according to ehcache/ehcache3#2946 (comment), EhCache 3 already supports Jakarta EE namespace.

[wilkinsona]

Thanks. We're already aware of that issue and its developments. As it describes, they published "an early alpha" a couple of weeks ago with EE 9 support but "there is no set schedule for a GA of that right now". We'll hopefully reinstate support for EhCache 3 once things have settled down a bit more.

[chrisdennis]

@wilkinsona Right now the pre-release version of Ehcache 3.10.0 that supports Jakarta only switched to Jakarta for JAXB (XML config parsing usages). The transactions module has not yet been released in a form that supports the Jakarta namespaces JTA spec. Would that also be a requirement for restoring support in spring-boot?

[wilkinsona]

Thanks, @chrisdennis. It would, yes. We need all of Ehcache's modules to be Jakarta EE 9-compatible before we can restore support.