Thanks for pointing it out @Baachi . The `content_length` attribute is represented as a string so I wanted to take a defensive approach, but I admit I was not aware about php automatic conversion with '>' and other arithmetic comparison operators.
Anyway I'm in favour of the more generic check `return ($this->tryGetObject($key) !== false)`. I just want to make few tests to see if it would work properly.

Ping @james75