Returns the appropriate AssociationSet with for given association. 
      Syntax
         
         
            public 
            abstract IODataAssociationSet  
            getAssociationSet
            (
            String 
            association
            )
         
      
      Parameters
         
         
            - 
               association – 
               The association of the AssociationSet
            
 
         
       
      Returns
         The appropriate AssociationSet with for given association