RCS1261: "Resource can be disposed asynchronously" does not take lock statement into account

[NoahStolk]

Product and Version Used:

Roslynator.Analyzers 4.9.0

Steps to Reproduce:

Consider the following code:

object fileStreamLock = new();

await SomeAsyncMethod();

async Task SomeAsyncMethod()
{
	lock (fileStreamLock)
	{
		using FileStream fs = new("test.txt", FileMode.OpenOrCreate);
		// Do something...
	}

	await Task.Yield(); // For demonstration purposes
}

RCS1261 is reported, saying that the FileStream can be disposed asynchronously, but doing so results in compiler error CS1996 (Cannot 'await' in the body of a 'lock' statement). This is not valid C#:

lock (fileStreamLock)
{
        await using FileStream fs = new("test.txt", FileMode.OpenOrCreate);
}