@Test
  public void testEvictOrphansWithinGracePeriod() throws Exception {
    BucketCache bucketCache = testEvictOrphans(60 * 60 * 1000L);
    assertEquals(18, bucketCache.getBackingMap().size());
    assertTrue(bucketCache.blocksByHFile.stream()
      .filter(key -> key.getHfileName().equals("testEvictOrphans-orphan")).count() > 0);
  }
This test is for HBASE-26295, {@link BucketEntry} which is restored from a persistence file
could not be freed even if corresponding {@link HFileBlock} is evicted from
{@link BucketCache}.
hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/bucket/TestBucketCache.java