title: odataV4 filter contains with case sensitive and incase sensitive
body: <p>i have tried to filter contains with case sensitive in oData.  but it not working. please find the query string</p>
  
  <pre><code>http://services.odata.org/V4/Northwind/Northwind.svc/Employees/?$filter=contains(toupper(FirstName),%27C%27)
  
  http://services.odata.org/V4/Northwind/Northwind.svc/Employees/?$filter=contains(tolower(FirstName),%27C%27)
  </code></pre>
  
  <p>it return both lower and upper case . it is possible to achieve?</p>