public StreamNode parse(String stream) {
		return parse(null, stream);
	}
Parse a stream definition without supplying the stream name up front. The stream name may be embedded in the
definition. For example: <code>mystream = http | file</code>

@return the AST for the parsed stream
spring-xd-dirt/src/main/java/org/springframework/xd/dirt/stream/dsl/StreamConfigParser.java