public void resolve(StreamLookupEnvironment env, String expressionString) {
		if (sourceChannelNode != null) {
			sourceChannelNode.resolve(env, expressionString);
		}
	}
Find the first reference to the named module in the stream. If the same module is referred to multiple times the
secondary references cannot be accessed via this method.

@return the first occurrence of the named module in the stream
spring-xd-dirt/src/main/java/org/springframework/xd/dirt/stream/dsl/StreamNode.java