@Override
	public boolean exists(String s) {
		return findOne(s) != null;
	}
Provides the key for a named metric. By default this appends the name to the metricPrefix value.

@param metricName the name of the metric
@return the redis key under which the metric is stored
spring-xd-analytics/src/main/java/org/springframework/xd/analytics/metrics/redis/AbstractRedisMetricRepository.java