The org.jboss.as.ejb3.remote.ImportedTransactionCache class was added as a result of fix for bz 1378454. This fix was rejected and pulled out but the class was left and now it's causing memory leak since any transactions in hte cache never expire.
Verified with EAP 6.4.17.CP.CR3
Released on 2017-09-05 as part of the EAP 6.4.17 release.