JBoss.orgCommunity Documentation
It's JBossCache class registered as eXo container component in configuration.xml file.
<component> <key>org.jboss.cache.transaction.TransactionManagerLookup</key> <type>org.jboss.cache.transaction.JBossStandaloneJTAManagerLookup</type> </component>
JBossStandaloneJTAManagerLookup used in standalone environment. Bur for Application Server environment use GenericTransactionManagerLookup.