MULE-6485: useContinuations parameter failure
_ fix for ConcurrentModificationException when sending response.
(cherry picked from commit ca7bc2277931e8b8fca97a2e9b04d3920aa81b74)

Conflicts:

	transports/jetty/src/main/java/org/mule/transport/servlet/jetty/JettyContinuationsReplyToHandler.java
(cherry picked from commit f427f065179d9fb742cec9ff5d68a90ca7a42ccf)
(cherry picked from commit 4c8e1d8292a4207270551c8105cd717ea3935fbe)