code: public void getActiveTransactions(Set<PersistentTranId> transactionList) throws MessageStoreException
     {
       if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
         SibTr.entry(tc, "getActiveTransactions", transactionList);
       
       AbstractItem item = null;
       
       NonLockingCursor cursor = newNonLockingItemCursor(
           new Filter() {
              public boolean filterMatches(AbstractItem abstractItem) throws MessageStoreException {
                if (abstractItem.isRemoving())
                  return true;
                else
                  return false;
              }      
         
           });
       
       cursor.allowUnavailableItems();
      
       while(null != (item = cursor.next()))
       {
         // Add matching tran id to the set
         transactionList.add(item.getTransactionId());
       }     
       
       if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
         SibTr.exit(tc, "getActiveTransactions");
     }
docs: getActiveTransactions - This method iterates through all msgs on the
  itemstream in Removing state and builds a list of all transaction ids
  involved in the remove