Reflection Adapter vs. non-empty-string

[ondrejmirtes]

This PR #1234 made Adapter reflection incompatible with the native PHP reflection. The native reflection returns false in has* methods if it's asked about nonexistent elements, and throws ReflectionException in get* methods: https://3v4l.org/YebV9

But the assert($name !== ''); calls are unforgiving even for has* methods. The current situation isn't great, because these methods have string in parameter types but reject '' at runtime. So currently these problems cannot be detected and avoided with static analysis.

I'd prefer if the Adapter namespace matched the behaviour of native reflection:

For has* methods, instead of the assert, do this:

if ($s === '') {
    return false;
}

For get* methods, throw ReflectionException for empty strings.

Thank you.

[Ocramius]

Doing this in the adapters sounds good 👍