Remove unused code.

Signed-off-by: Marios Sotiropoulos <mai1211@uom.edu.gr>
Make the ObjectRepository field of the Request classes optional.

Signed-off-by: Marios Sotiropoulos <mai1211@uom.edu.gr>
Add property "oauthServerUri" to class AccessTokenRequest.

Signed-off-by: Marios Sotiropoulos <mai1211@uom.edu.gr>