@Nullable
    public static Accumulator getAccumulatorOrNull(QueryCacheContext context,
                                                   String mapName, String cacheId, int partitionId) {
        PartitionAccumulatorRegistry accumulatorRegistry = getAccumulatorRegistryOrNull(context, mapName, cacheId);
        if (accumulatorRegistry == null) {
            return null;
        }
        return accumulatorRegistry.getOrNull(partitionId);
    }
@Test
    public void getAccumulatorOrNull_whenNoAccumulatorsRegistered_thenReturnNull() {
        Accumulator accumulator = getAccumulatorOrNull(context, "myMap", "myCache", -1);

        assertNull(accumulator);
    }