public Recycler createRecycler(final BucketEntry bucketEntry) {
    return () -> {
      freeBucketEntry(bucketEntry);
      return;
    };
  }
<pre>
Create the {@link Recycler} for {@link BucketEntry#refCnt},which would be used as
{@link RefCnt#recycler} of {@link HFileBlock#buf} returned from {@link BucketCache#getBlock}.
NOTE: for {@link BucketCache#getBlock},the {@link RefCnt#recycler} of {@link HFileBlock#buf}
from {@link BucketCache#backingMap} and {@link BucketCache#ramCache} are different:
1.For {@link RefCnt#recycler} of {@link HFileBlock#buf} from {@link BucketCache#backingMap},
  it is the return value of current {@link BucketCache#createRecycler} method.

2.For {@link RefCnt#recycler} of {@link HFileBlock#buf} from {@link BucketCache#ramCache},
  it is {@link ByteBuffAllocator#putbackBuffer}.
</pre>
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/BucketCache.java