code: private static void touch(final Node node, final Calendar modified, final String modifyingUser) {
          touch(node, null, null, modified, modifyingUser);
      }
docs: Updates the LAST_MODIFIED_DATE and LAST_MODIFIED_BY properties to the provided values.
  
  @param node The JCR node
  @param modified the modification date, or null if not explicitly set
  @param modifyingUser the userID who modified this resource or null if not explicitly set