code: public function validateRequiredFields($postVars)
      {
          $requiredFields = $this->getRequiredFields($postVars['id']);
          $missingKeys = array();
          
          foreach ($requiredFields as $human => $keys) {
              if (!$this->hasRequiredValue($postVars, $keys)) {
                  $missingKeys[] = $human;
              }
          }
          
          if (!empty($missingKeys)) {
              throw new GreenhouseApplicationException('Submission missing required answers for: ' . implode(', ', $missingKeys));
          }
          
          return true;
      }
docs: Method ensures that a non-empty response is contained in all fields marked as required.  If not,
  an Exception is thrown.
  
  @params  Array   $postVars   The Greenhouse-formatted post parameters.
  @return  boolean
  @throws  GreenhouseApplicationException