Fix EhCache hit/miss ratio

The hitRatio is the ratio of two windowed rates that are calculated
independently. They are not updated or read transactionally, hence the
ratio of the two can drift slightly from what might be expected.

We now make sure that the hit or miss ratio can't be higher than 1

Closes gh-3235

Author: izeye

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/cache/EhCacheStatisticsProvider.java

@@ -37,8 +37,8 @@ public CacheStatistics getCacheStatistics(CacheManager cacheManager,
 		statistics.setSize(ehCacheStatistics.getSize());
 		Double hitRatio = ehCacheStatistics.cacheHitRatio();
 		if (!hitRatio.isNaN()) {
-			statistics.setHitRatio(hitRatio);
-			statistics.setMissRatio(1 - hitRatio);
+			statistics.setHitRatio(hitRatio > 1 ? 1 : hitRatio);
+			statistics.setMissRatio(hitRatio > 1 ? 0 : 1 - hitRatio);
 		}
 		return statistics;
 	}