With WebLogic 12.2, Oracle Coherence has updated names for all of it's system property overrides. The "tangosol" prefix is dropped, leaving for much simpler system property names.
The property we are interested in is...
coherence.cacheconfig
The value of this property needs to be set to the path of the custom Coherence cache configuration file. This should be done in the setUserOverrides script for WebLogic. For example...
setUserOverrides
EXTRA_JAVA_PROPERTIES="-Dcoherence.cacheconfig=/my/config/coherence-cache-config.xml"
Once that is done, every time WebLogic is started, the Coherence cache configuration will be read from your custom file. This will impact all Coherence applications running in the WebLogic server. You can still use other cache configuration files on a per-application basis if needed though.
-i