ThresholdingOutputStream never calls thresholdReached() when threshold < 0

After 2.16.0, if ThresholdingOutputStream is created with a threshold less than 0, such as -1, it will never call thresholdReached().

Specifically, in checkThreshold(final int count), thresholdExceeded is now already true, so the condition is never met.

if (!thresholdExceeded && written + count > threshold) {
    thresholdExceeded = true;
    thresholdReached();
}

This leads to a problem in DeferredFileOutputStream, because it extends ThresholdingOutputStream. DeferredFileOutputStream relies on thresholdReached() to know when to create a temp file. Now the temp file is never created. This, in turn, leads to a problem in commons-fileupload DiskFileItem. This, in turn, leads to problem in Struts2 JakartaMultiPartRequest.

It seems an oversight that thresholdReached() is never called. The documentation for that method says:

Indicates that the configured threshold has been reached, and that a subclass should take whatever action necessary on this event. This may include changing the underlying output stream.

There is now no longer any notification to subclasses, which can cause a cascade of problems.

This seems to be the commit that introduced the change: https://github.com/apache/commons-io/commit/4f144cf02cfb5f72184bfef40efd8f99a4278ba8, seems to be related to IO-405.