Added None check for association_type_ in to_obj()

Author: ikiril01

cybox/core/associated_object.py

@@ -20,7 +20,7 @@ def __init__(self, type_=None, association_type_=None, defined_object=None):
 
     def to_obj(self):
         obj = super(AssociatedObject, self).to_obj(core_binding.AssociatedObjectType())
-        obj.set_Association_Type(self.association_type_.to_obj())
+        if self.assocation_type is not None : obj.set_Association_Type(self.association_type_.to_obj())
         return obj
 
     def to_dict(self):