fileDefaultScheme example

        }
      }
    }
  }

  /** * {@inheritdoc} */
  public function buildUri($uri) {
    $source_scheme = $scheme = StreamWrapperManager::getScheme($uri);
    $default_scheme = $this->fileDefaultScheme();

    if ($source_scheme) {
      $path = StreamWrapperManager::getTarget($uri);
      // The scheme of derivative image files only needs to be computed for       // source files not stored in the default scheme.       if ($source_scheme != $default_scheme) {
        $class = $this->getStreamWrapperManager()->getClass($source_scheme);
        $is_writable = NULL;
        if ($class) {
          $is_writable = $class::getType() & StreamWrapperInterface::WRITE;
        }