This is a left-over from very old code, which pre-dates the introduction of the `PDFDocumentLoadingTask` and it's nothing more than an alias for its `destroy` method.
Given that `PDFDocumentProxy` already provides a way to access the underlying `PDFDocumentLoadingTask` instance, it shouldn't be necessary to have an alias for one of its methods.
*Please note:* For any existing code relying on the removed method, updating it should be as simple as replacing `pdfDocument.destroy()` with `pdfDocument.loadingTask.destroy()`.
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[1] If the `PDFDocumentProxy` class was added today, there's no chance that it'd include a `destroy` method.
Currently it's only possible to trigger page-render debugging through the page number, but when looking at the /Pages tree it's often not immediately obvious what the page number actually is.
However, the /Ref of the page is directly available and it's thus handy to be able to use that one instead to enable page-render debugging.
Instead of having all the code for the new debugger in a single file,
split it into multiple files.
This makes it easier to navigate and maintain the codebase.
It'll be make hacking and fixing bugs in the debugger easier.
