[12.x] Default $contents as empty string for Filesystem::put()

[weshooper]

Non-breaking change, since currently the second parameter must be provided.

When testing file operations, we often don't care about the content, so put() empty strings.

Making that explicit, by not providing content, would also be consistent with the behaviour of assertExists() where content is optional.

-$fs->put('file.foo', '');
-$fs->put('file.bar', '');
+$fs->put('file.foo');
+$fs->put('file.bar');
$fs->assertExists('file.foo');
$fs->assertExists('file.bar');

[AndrewMast]

I personally think that the file contents should stay explicit. Do we have any default file contents elsewhere in the framework?

[taylorotwell]

Thanks for your pull request to Laravel!

Unfortunately, I'm going to delay merging this code for now. To preserve our ability to adequately maintain the framework, we need to be very careful regarding the amount of code we include.

If applicable, please consider releasing your code as a package so that the community can still take advantage of your contributions!