Get use statement from class

Not quite sure of the best title but I will explain what I am asking as best I can. Assume I have the following file:

MyCustomClass.php

<?php    

namespace MyNamespace;

use FooNamespace\FooClass;
use BarNamespace\BarClass as Bar;
use BazNamespace\BazClass as BazSpecial;

class MyCustomClass {

    protected $someDependencies = [];

    public function __construct(FooClass $foo, Bar $bar) {

        $someDependencies[] = $foo;
        $someDependencies[] = $bar;
    }
}

Now if I were to use reflection, I could get the fully qualified class names from the type hints in the construct.

However, I would recieve FooNamespace\FooClass and BarNamespace\BarClass. Not, FooNamespace\FooClass and BarNamespace\Bar. I would also get no reference to BazNamespace\BazClass.

Basically, my question is: How can I get the fully qualified names from MyCustomClass.php while only knowing FooClass, Bar, and, BazSpecial?

I do not want to use a file parser as this will eat performance. I want to be able to do something like:

$class = new ReflectionClass('MyCustomClass');
...
$class->getUsedClass('FooClass'); // FooNamespace\FooClass
$class->getUsedClass('Bar'); // BarNamespace\BarClass
$class->getUsedClass('BazSpecial'); // BazNamespace\BazClass

How would I go about doing this?