private static boolean validateFilterUser(String username, String filterUser,
    List<String> filterUserGroups) {
    if (filterUserGroups == null) {
      // Validate user name or group names whether equal
      if (filterUser.equals(username)) {
        return true;
      }
    } else {
      // Check whether filter user belongs to the cell key group.
      return filterUserGroups.contains(username.substring(1));
    }
    return false;
  }
Parse and filter permission based on the specified column family, column qualifier and user
name.
hbase-server/src/main/java/org/apache/hadoop/hbase/security/access/PermissionStorage.java