public SimpleFileSink mode(String mode) {
		Assert.hasText(mode, "monde can not be null nor empty");
		this.mode = mode;
		return this;
	}
Establishes the mode in which the SimpleFileSink.  
@param mode determines if the file existing file should be REPLACE, APPEND, etc 
@return the current instance of the simple file sink.
spring-xd-test-fixtures/src/main/java/org/springframework/xd/test/fixtures/SimpleFileSink.java