code: public Response andContentType(String contentType) {
          Objects.requireNonNull(contentType, Required.CONTENT_TYPE.toString());
          this.contentType = contentType;
          this.headers.put(Header.CONTENT_TYPE.toHttpString(), contentType);
  
          return this;
      }
docs: Sets a specific content type to use for the response. Default is "text/html"
  
  @param contentType The content type to use
  @return A response object {@link io.mangoo.routing.Response}