Unable to disable ProducerCache

Issue

It is not possible to disable ProducerCache for camel-rabbitmq, camel-netty4, camel-netty and camel-jms producers.

For example, while trying to turn off activemq ProducerCache like:

<wireTap uri="activemq:foo" cacheSize="-1" />

results in error :

java.util.concurrent.RejectedExecutionException
    at org.apache.camel.component.jms.JmsProducer.process(JmsProducer.java:144)