Proxy tokens are broken for hftp. The impact is systems using proxy tokens, such as oozie jobs, cannot use hftp.
Support doAs and GETHOMEDIRECTORY in webhdfs
Backport HDFS-3553 (hftp proxy tokens) to branch-1
WebHdfsFilesystem does not work within a proxyuser doAs call in secure mode
AbstractDelegationTokenIdentifier#getUser() should set token auth type