code: public void addAccessControlEntry() {
  
          try {
              if ((m_resource == null) || !m_importACEs) {
                  // skip ace import if not intended or the import of the resource failed
                  return;
              }
              if (m_throwable != null) {
                  // user or group of ACE might not exist in target system, ignore ACE
                  if (LOG.isWarnEnabled()) {
                      LOG.warn(
                          Messages.get().getBundle().key(
                              Messages.LOG_IMPORTEXPORT_ERROR_IMPORTING_ACE_1,
                              getCms().getRequestContext().removeSiteRoot(m_resource.getRootPath())),
                          m_throwable);
                  }
                  getReport().println(m_throwable);
                  getReport().addError(m_throwable);
                  return;
              }
              if (m_aces == null) {
                  // this list will be used and clean up in the importResource and importAccessControlEntries methods
                  m_aces = new ArrayList<CmsAccessControlEntry>();
              }
              m_aces.add(
                  new CmsAccessControlEntry(
                      m_resource.getResourceId(),
                      m_acePrincipalId,
                      m_acePermissionsAllowed,
                      m_acePermissionsDenied,
                      m_aceFlags));
          } finally {
              m_throwable = null;
              m_acePrincipalId = null;
              m_acePermissionsAllowed = 0;
              m_acePermissionsDenied = 0;
              m_aceFlags = 0;
          }
      }
docs: Adds an ACE from the current xml data.<p>
  
  @see #addResourceAceRules(Digester, String)