code: public void setContentTypeEngine(ContentTypeEngine engine) {
          String contentType = engine.getContentType();
          String suffix = StringUtils.removeStart(contentType.substring(contentType.lastIndexOf('/') + 1), "x-");
  
          engines.put(engine.getContentType(), engine);
          suffixes.put(suffix.toLowerCase(), engine);
  
          log.debug("'{}' content engine is '{}'", engine.getContentType(), engine.getClass().getName());
      }
docs: Sets the engine for it's specified content type. An suffix for the engine is also registered based on the
  specific type; extension types are supported and the leading "x-" is trimmed out.
  
  @param engine