code: protected function applyAnalyzer(array $mapping, Field $field, \stdClass $rootObject, $path = null)
      {
          if (null === $this->defaultAnalyzer) {
              return $mapping;
          }
  
          if (!isset($mapping['type']) || 'text' !== $mapping['type']) {
              return $mapping;
          }
  
          if (isset($mapping['index']) && false === $mapping['index']) {
              return $mapping;
          }
  
          if (isset($mapping['analyzer'])) {
              return $mapping;
          }
  
          $mapping['analyzer'] = $this->defaultAnalyzer;
          return $mapping;
      }
docs: Modify the analyzer for a property prior to adding it to the document mapping.
  This is only applied to "text" types.
  
  @param array     $mapping
  @param Field     $field
  @param \stdClass $rootObject
  @param null      $path
  
  @return array