presto-hive/src/main/java/io/prestosql/plugin/hive/authentication/ImpersonatingHdfsAuthentication.java/ImpersonatingHdfsAuthentication/createProxyUser
class ImpersonatingHdfsAuthentication:    private UserGroupInformation createProxyUser(String user)
    {
        return UserGroupInformation.createProxyUser(user, hadoopAuthentication.getUserGroupInformation());
    }