Support for expression in JGroups property element

When trying to set a property for the protocol TCPPING like this:

<protocol type="TCPPING" socket-binding="jgroups-tcpping">
<property name=”initial_hosts”>${initial_hosts}</property>
</protocol>

we get a parser error on startup (${initial_hosts} is set in a property
file we have specified with -P). Doing a :read-resource-attributes via
CLI reveals that the property element doesn't support expressions.

Are there plans to support this in the future or is there a specific
reason why this isn't supported for this specific element?