The versionRequest() call does not return any sensitive information. It is mainly used for sanity checks. The presence of checkSuperuserPrivilege() forces users to run datanode as a hdfs superuser.
In secure setup, a keytab obtained from a compromised datanode can allow the intruder to gain hdfs superuser privilege. We should allow datanodes to be run as non-hdfs-superuser by removing checkSuperuserPrivilege() from versionRequest().