Unable to add custom interceptors declaratively to server config

Per Tristan Tarrant, creating jira ticket:

I've upgraded from Infinispan 5.2.5 to Infinispan server 5.3 and it looks like the configuration file (urn:infinispan:server:core:5.3) doesn't support declaring custom interceptors as jboss-infinispan-core_5_3.xsd does not have the necessary elements. [I did try just adding the custom interceptor elements and got a parse error].