The TEST_CALLBACK value is a string as following:
ESBClassname1:callbackImplClassname1;ESBClassname2:callbackImplClassname2
Note that the ESBClassname is the full name of a ESB product class, including the package name. The callbackImplClassname is the full name of the callback implementation for the ESBClassname class.
Example of TEST_CALLBACK setup:
TEST_CALLBACK com.sonicsw.xq.connector.jms.JMSEndpoint:qa.b2b.whitebox.XOCallback;com.sonicsw.xq.connector.jms.messagingbean.Session:qa.b2b.whitebox.XOCallback