AOP: JointPoint->hasMethodArgument does not recognize NULL

Description

I created a aspect for tracking model changes (executing on every setter).
To assure that argument is passed, I check the jointPoint for the method-argument.
As the model attribute value has been changed from a value (e.g. object) to null, I would like to track that it changed. But: $joinPoint->isMethodArgument('propertyName') returns false. Although getArguments returns [propertyName => NULL]

The problem is here:
https://github.com/neos/flow-development-collection/blob/a2d086a2a38c369a455f2e7cb2449f7df4f09cb6/Neos.Flow/Classes/Aop/JoinPoint.php#L176

isset does return false, if value is set to NULL. Therfore, array_key_exists should be used:

    public function isMethodArgument($argumentName)
    {
        return array_key_exists($argumentName, $this->methodArguments);
    }

quickwin ;)

Expected behavior

JointPoint with arguments: ['myAttribute' => NULL]
Method isMethodArgument('myAttribute') should return true

Actual behavior

returns false

Affected Versions

Neos: latest (but code exists more than 2 years)
Flow: latest

Start in Neos.Flow/Classes/Aop/JoinPoint.php at the isMethodArgument method and review how methodArguments is checked for a NULL value. Verify the reported case where getArguments contains myAttribute => NULL, and confirm that isMethodArgument('myAttribute') returns true afterward.