}
		groups.Remove(group)
		c.iamUserGroupMemberships[member] = groups
	}
}

// policyDBGet - lower-level helper; does not take locks.
//
// If a group is passed, it returns policies associated with the group.
//
// If a user is passed, it returns policies of the user along with any groups
// that the server knows the user is a member of.
//
// In LDAP users mode, the server does not store any group membership

   * the two sets. If you have reason to believe one of your sets will generally be smaller than the
   * other, pass it first. Unfortunately, since this method sets the generic type of the returned
   * set based on the type of the first set passed, this could in rare cases force you to make a
   * cast, for example:
   *
   * <pre>{@code
   * Set<Object> aFewBadObjects = ...
   * Set<String> manyBadStrings = ...
   *

   * IllegalArgumentException} if passed a {@code fromKey} less than an earlier {@code fromKey}.
   * However, this method doesn't throw an exception in that situation, but instead keeps the
   * original {@code fromKey}. Similarly, this method keeps the original {@code toKey}, instead of
   * throwing an exception, if passed a {@code toKey} greater than an earlier {@code toKey}.
   */
  @Override

			return nil, errDiskAccessDenied
		}
		storageLogOnceIf(GlobalContext, err, "check-format-json") // log unexpected errors
		return nil, errCorruptedBackend
	}
	return fi, nil
}

// GetDiskID - returns the cached disk uuid
func (s *xlStorage) GetDiskID() (string, error) {
	s.RLock()
	diskID := s.diskID
	fileInfo := s.formatFileInfo
	lastCheck := s.formatLastCheck

    Iterator<String> itr2 = Iterators.concat(itr1, singletonIterator("d"));
    assertEquals("c", itr2.next());
    assertEquals("d", itr2.next());
  }

  /** Illustrates the somewhat bizarre behavior when a null is passed in. */
  public void testConcatContainingNull() {
    Iterator<Iterator<Integer>> input =
        (Iterator<Iterator<Integer>>)
            Arrays.<@Nullable Iterator<Integer>>asList(iterateOver(1, 2), null, iterateOver(3))