code: @Override
      public FilenameFilter getFilenameFilter(String mediaType) {
          if (mediaType == null) {
              return null;
          }
  
          if (MediaType.NATIVE_MEDIATYPE_SYNTAX_MAP.containsKey(mediaType)) {
              return new FilenameFilterBySyntax(MediaType.NATIVE_MEDIATYPE_SYNTAX_MAP.get(mediaType));
          } else if (this.getServiceTransformationEngine().canTransform(mediaType)) {
              return this.getServiceTransformationEngine().getFilenameFilter(mediaType);
          }
  
          return null;
      }
docs: Gets the corresponding filename filter to a given media type by checking both native formats
  and those supported through transformation
  
  @param mediaType the media type for which to obtain the file extension
  @return the filename filter or null if it is not supported. Callers are advised to check
  first that the media type is supported @see canTransform .