code: public function getItemHref(QtiRunnerServiceContext $context, $itemIdentifier)
      {
          $href = false;
  
          $indexFile = $this->getItemHrefIndexFile($context, $itemIdentifier);
  
          if ($indexFile->exists()) {
              $href = $indexFile->read();
          } else {
              if (!isset($this->itemHrefIndex)) {
                  $storage = $this->getServiceLocator()->get(ExtendedStateService::SERVICE_ID);
                  $this->itemHrefIndex = $storage->loadItemHrefIndex($context->getTestExecutionUri());
              }
  
              if (isset($this->itemHrefIndex[$itemIdentifier])) {
                  $href = $this->itemHrefIndex[$itemIdentifier];
              }
          }
  
          return $href;
      }
docs: Gets AssessmentItemRef's Href by AssessmentItemRef Identifier.
  
  Returns the AssessmentItemRef href attribute value from a given $identifier.
  
  @param QtiRunnerServiceContext $context
  @param string $itemIdentifier
  @return boolean|string The href value corresponding to the given $identifier. If no corresponding href is found, false is returned.