public void setIntegrationEvaluationContext(EvaluationContext evaluationContext) {
        this.evaluationContext = evaluationContext;
        this.evaluationContextSet = true;
    }
Construct a new MessageHandler given the reactor based Processor to delegate
processing to and a partition expression.

@param processor The stream based reactor processor
spring-xd-reactor/src/main/java/org/springframework/xd/reactor/MultipleBroadcasterMessageHandler.java