code: public void changeAccessMode(String principal, boolean isGroup, HostAccessMode accessMode) throws AuthMinimumAdminPermission, InvalidArgument, RuntimeFault, SecurityError, UserNotFound, RemoteException {
          getVimService().changeAccessMode(getMOR(), principal, isGroup, accessMode);
      }
docs: Update the access mode for a user or group.
  If the host is in lockdown mode, this operation is allowed only on users in the exceptions list - see
  {@link com.vmware.vim25.mo.HostAccessManager#queryLockdownExceptions QueryLockdownExceptions}, and trying to
  change the access mode of other users or groups will fail with SecurityError.
  
  @param principal  The affected user or group.
  @param isGroup    True if principal refers to a group account, false otherwise.
  @param accessMode AccessMode to be granted. AccessMode#accessOther is meaningless and will result in InvalidArgument exception.
  @throws AuthMinimumAdminPermission
  @throws InvalidArgument
  @throws RuntimeFault
  @throws SecurityError
  @throws UserNotFound
  @throws RemoteException