Fix build warning.
Fix build warning.

hubuk/CodeContracts,hubuk/CodeContracts,hubuk/CodeContracts,ndykman/CodeContracts,Microsoft/CodeContracts,Microsoft/CodeContracts,Microsoft/CodeContracts,ndykman/CodeContracts,hubuk/CodeContracts,hubuk/CodeContracts,ndykman/CodeContracts,hubuk/CodeContracts,Microsoft/CodeContracts,Microsoft/CodeContracts,Microsoft/CodeContracts,hubuk/CodeContracts,ndykman/CodeContracts,ndykman/CodeContracts,ndykman/CodeContracts,Microsoft/CodeContracts,ndykman/CodeContracts