Reviewing for merge; I'll likely make the following changes when I do.

First, import `ReflectionClass`.

Second, the can be simplified and branched a little cleaner.

```php
if ($this->isArray()) {
    return 'array';
}

if (($class = $this->getClass()) instanceof ReflectionClass) {
    return $class->getName();
}

$docBlock = $this->getDeclaringFunction()->getDocBlock();

if (!$docBlock instanceof DocBlock) { // or whatever the type is
    return null;
}

$params = $docBlock->getTags('param');
if (isset($params[$this->getPosition()])) {
    return $params[$this->getPosition()]->getType();
}

return null;
```

The reason I suggest this approach is that it becomes easier to pair the conditions to the return type, which makes it a bit simpler to read, as well as to identify the specific behaviors.
if ($docBlock = $this->getDeclaringFunction()->getDocBlock()) {