Nullable Typehint is not detected as nullable

[wendelb]

Describe the bug
A clear and concise description of what the bug is.

Code sample

class MyClass {
    private function myFunction(ClassA|ClassB|null $param): bool {
    }
}

To reproduce
Steps to reproduce the behavior:

1. Acquire the method parameters in a Sniff that is registered for functions (\PHP_CodeSniffer\Files\File::getMethodParameters)
2. Test if the only parameter is nullable

Actual behavior
The Type Hint is detected as ClassA|ClassB|null, but the property "nullable_type" is set to false.

Expected behavior
PHPCS should be able to detect that the $param parameter is nullable

Versions (please complete the following information):

• OS: N/A (Ubuntu, some current version)
• PHP: 8.1
• PHPCS: 3.7.1
• Standard: N/A

Additional context
The Sniff here https://github.com/spryker/code-sniffer/blob/master/Spryker/Sniffs/Commenting/DocBlockParamAllowDefaultValueSniff.php is using get getMethodParameters method to validate docblock and typehint. Due to wrong input from PHPCS it create a violation where none should be.

[jrfnl]

This is intentional and was discussed in detail when support for union types was implemented. Please read the discussion here: #2968 (comment)

[gsherwood]

Hopefully that linked comment from @jrfnl helped explain the behaviour.