"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

spring-httpserver-timings/src/main/java/io/github/sercasti/tracing/filter/TracingFilter.java

Line 43 in 6140ef2

filterChain.doFilter(request, response);

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.