"disabled" flag calls doFilter twice

[aakoch]

If you set the filter's disabled field to false, the filter will call doFilter twice.

Example:

@Bean
protected TracingFilter tracingServerTimingFilter() {
    TracingFilter tracingFilter = new TracingFilter();
    tracingFilter.setDisabled(true);
    return tracingFilter;
}

This will cause an exception to be thrown too: Caused by: java.lang.IllegalStateException: getWriter() has already been called for this response

https://github.com/sercasti/spring-httpserver-timings/blob/6140ef2aaefdf533533f202b36e18bd4d31b071c/src/main/java/io/github/sercasti/tracing/filter/TracingFilter.java#L43

Also, after adding this to my application, all my Ajax responses seem to have no content. I'm thinking something's wrong in the HttpServletResponseCopier class.