getOccupiedByteSize() is not working when Heap entries is mentioned in ResourcePoolsBuilder

[DanaWhite30]

Using ehcache 3.10

StatisticsService statisticsService = new DefaultStatisticsService();

CacheManager cacheManager = CacheManagerBuilder.newCacheManagerBuilder()
                .using(statisticsService)
                .build(true);

CacheConfiguration config = CacheConfigurationBuilder.newCacheConfigurationBuilder(String.class, String.class,
        ResourcePoolsBuilder.newResourcePoolsBuilder().heap(10)).build();  // heap 10 entries
Cache<String, String> cache = cacheManager.createCache("preConfigured",config);
cache.put("key1", "value1");
cache.put("key2", "value2");
cache.put("key3", "value3");

long currentMemory = statisticsService.getCacheStatistics("preConfigured").getTierStatistics().get("OnHeap").getOccupiedByteSize();
System.out.println(currentMemory);  // -1 is printed

when ResourcePoolsBuilder is changed to use memory size it works fine.

[chrisdennis]

Heap tiers that are entry sized do not track their byte sizes by design since the sizing operations that would be needed carry significant overhead.

[DanaWhite30]

Is there any other way to calculate the heap size of the cache object ?