public KafkaSink topic(String topic) {
		Assert.hasText(topic, "topic must not be empty nor null");
		this.topic = topic;
		return this;
	}
Set the topic that the sink will publish to

@param topic the topic the sink will publish
@return instance of the kafka sink
spring-xd-test-fixtures/src/main/java/org/springframework/xd/test/fixtures/KafkaSink.java