Girder over which Beam extends to cantilever designed as composite

In the scenario attached, Girder #1 is under the Beam #2 (and other parallel beams) cantilevering over it. If the whole floor systeme is modeled as composite, how is the Girder #1 being designed as composite beam? Since the deck would not be over it, should it not be designed as non-composite? 

Thank in advance!