I suggest the following for documentation: When reading and writing instances of custom classes via HotRod client, and the client is installed as part of client modules in EAP, the custom classes should be packaged in a separate module in EAP and a dependency on this module should be added to ${EAP_HOME}/modules/system/layers/base/org/infinispan/commons/jdg-6.x/module.xml. Otherwise the classes won't be visible to the HotRod client references by an application deployed in EAP.
This topic has been added and published; a link to the section on the customer portal is below: https://access.redhat.com/documentation/en-US/Red_Hat_JBoss_Data_Grid/6.6/html-single/Getting_Started_Guide/index.html#Using_Custom_Classes_with_the_Hot_Rod_Client