DPDP02_g2.cs

public class OpportunityRepository : IOpportunityRepository
{
    protected Dyn365ServiceContext serviceContext;

    public OpportunityRepository(IOrganizationService service)
    {
        this.serviceContext = new Dyn365ServiceContext(service); 
    }

    public Opportunity GetById(Guid id)
    {
        return this.serviceContext.OpportunitySet.FirstOrDefault(o => o.Id == id);
    }

    public void Create(Opportunity opportunity)
    {
        this.serviceContext.AddObject(opportunity);
    }

    public void SaveChanges()
    {
        this.serviceContext.SaveChanges();
    }

    public void Dispose()
    {
        this.serviceContext.Dispose(); 
    }

}