We are moving HDFS-related code from RocksDB main repo to an external plug-in. The HDFS-related code is not well maintained and tested. See more background and discussion in #9067.
Going forward, we plan to treat it as an external plugin, similar to an example demonstrated by @ajkr in https://github.com/ajkr/dedupfs.

I currently host a test-repo at https://github.com/riversand963/rocksdb-hdfs-env, until we figure out an official plan.
The current test-repo supports only C++, while Java binding for HDFS is not included.

cc @adamretter.