Description:
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The documented signature of extractTo() is:

public bool Phar::extractTo ( string $pathto [, string|array $files [, bool $overwrite = false ]] )

Consider that I want to extract all files from a Phar archive to a directory, overwriting existing files; I need to skip the $files parameter to set $overwrite to true.

With $files accepting string|array, I tried an empty string:

$phar->extractTo('dir', '', true);

But this yields an exception:
PharException: Phar Error: attempted to extract non-existent file ""

I also tried an empty array:

$phar->extractTo('dir', [], true);

But it does not extract any file.

Actually, the only thing that works to actually skip the $files parameter is to pass a null value:

$phar->extractTo('dir', null, true);

So it would be nice to document the fact that $files can accept null as well.

Expected result:
----------------
public bool Phar::extractTo ( string $pathto [, string|array|null $files [, bool $overwrite = false ]] )

...

files

The name of a file or directory to extract, or an array of files/directories to extract, or null to skip the parameter

Actual result:
--------------
public bool Phar::extractTo ( string $pathto [, string|array $files [, bool $overwrite = false ]] )

...

files

The name of a file or directory to extract, or an array of files/directories to extract