@Override
	public String getDefaultsPrefix() {
		return DEFAULTS_PREFIX;
	}
rocketMQ specific extended binding properties class that extends from
{@link AbstractExtendedBindingProperties}.

@author <a href="mailto:fangjian0423@gmail.com">Jim</a>
spring-cloud-alibaba-starters/spring-cloud-starter-stream-rocketmq/src/main/java/com/alibaba/cloud/stream/binder/rocketmq/properties/RocketMQExtendedBindingProperties.java