Write SQL query to solve given problem: What is the language of the method used in the solution path "opendns_diagnosticapp\windows\OpenDnsDiagnostic.sln"?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T2.Lang FROM Solution AS T1 INNER JOIN Method AS T2 ON T1.Id = T2.SolutionId WHERE T1.Path = 'opendns_diagnosticappwindowsOpenDnsDiagnostic.sln'