code: public static OperationBuilder setContentType(final String contentType)
     {
        return new Response() {
           @Override
           public void performHttp(final HttpServletRewrite event, final EvaluationContext context)
           {
              event.getResponse().setContentType(contentType);
           }
  
           @Override
           public String toString()
           {
              return "Response.setContentType(\"" + contentType + "\")";
           }
        };
     }
docs: Create an {@link Operation} that sets the content type for the {@link HttpServletResponse}