public Proposal Validate(Proposal proposal)
{
BaseValidator validatorChain = new LoanValueValidator();
validatorChain
.SetNext(new LoanMonthlyInStallmentsValidator())
.SetNext(new MinimumProponentQuantityValidator())
.SetNext(new MainProponentQuantityValidator())
.SetNext(new ProponentAgeValidator())
.SetNext(new WarrantyQuantityValidator())
.SetNext(new WarrantyValueValidator())
.SetNext(new WarrantyStateValidator())
.SetNext(new ProponentIncomeValidator());
validatorChain.Validate(proposal);
return(proposal.AsInvalid());
}