Class has Method but not Documented in API
I searched for the correct method to get the thumbnail URL for a file in the API documentation, but /Concrete/Core/Entity/File/File has no such method. So I searched the web for some answer and found $file->getThumbnailURL(). And it worked. Now I wondered what sort of class my $file could be and with get_class() I found it was this same /Concrete/Core/Entity/File/File! Now I searched the source code of this class and also didn't find any getThumbailURL method, whereas I found it in /Concrete/Core/Entity/File/Version.
Can anyone get me a hint? It seems I'm missing some basic concept...
So any non-existent method you call on an object of File type is automatically called on its corresponding Version object. That's why it's working.