hdfs effective_group

[smithnote]

I need download some from hdfs, when i use 'hadoop fs -D hadoop.job.ugi=username,groupname -get /my/hdfs/file/path', it work.
I use snakebite client and set effective_user, then copyToLocal, but its not work, it looks like permission issue,
so could provide a effective_group parameter, like hadoop command support "-D hadoop.job.ugi=username,groupname"