@AssertTrue(message = "the options topic and topics are mutually exclusive")
	public boolean isTopicOptionValid() {
		boolean isTopicValid = StringUtils.hasText(topic);
		boolean isTopicsValid = StringUtils.hasText(topics);
		boolean isOptionValid =   isTopicValid  ? !isTopicsValid : true;
		if (isOptionValid && (!isTopicsValid && !isTopicValid)) {
			this.topic = ModulePlaceholders.XD_STREAM_NAME;
			this.topics = this.topic;
		}
		else if (isOptionValid && isTopicValid) {
				this.topics = this.topic;
		}
		return isOptionValid;
	}
Module options for Kafka source module.

@author Ilayaperumal Gopinathan
@author Marius Bogoevici
extensions/spring-xd-extension-kafka/src/main/java/org/springframework/integration/x/kafka/KafkaSourceModuleOptionsMetadata.java