Is it thread-safe that NamenodeConnection?

[sunholee]

I have a question on the thread-safety of Client.
Client has the following fields, and NamenodeConnection seems to be guarded by its reqLock.
Is it thread-safe that NamenodeConnection?

type Client struct {
	namenode *rpc.NamenodeConnection
	options  ClientOptions

	defaults      *hdfs.FsServerDefaultsProto
	encryptionKey *hdfs.DataEncryptionKeyProto
}

If the connection is safe, then, by adding locks to other fields, I could get a thread-safe version of Client.
(I need a thread-safe fork, this is not a PR.)