Proton-j threading

Hello,

In the java doc for Driver interface I see:

"Unless otherwise stated, methods on Driver implementations are not
necessarily thread-safe."

and during testing I got:

Exception in thread "Proton Reactor" java.util.ConcurrentModificationException
at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:953)
at java.util.LinkedList$ListItr.next(LinkedList.java:886)
at org.apache.qpid.proton.messenger.impl.MessengerImpl$MessageAvailable.test(MessengerImpl.java:1094)
at org.apache.qpid.proton.messenger.impl.MessengerImpl.waitUntil(MessengerImpl.java:872)
at org.apache.qpid.proton.messenger.impl.MessengerImpl.waitUntil(MessengerImpl.java:853)
at org.apache.qpid.proton.messenger.impl.MessengerImpl.recv(MessengerImpl.java:451)
at org.apache.qpid.proton.messenger.impl.MessengerImpl.recv(MessengerImpl.java:456)

What is the best practice for threading when using proton-j?

Piotr