Added client credential grant type support and a test to prove it.

Fixes #33

1 files changed, 4 insertions, 2 deletions

diff --git a/src/DotNetOpenAuth.OAuth2/OAuth2/ChannelElements/IAuthorizationDescription.cs b/src/DotNetOpenAuth.OAuth2/OAuth2/ChannelElements/IAuthorizationDescription.cs
index 150a6a9..9c4219c 100644
--- a/src/DotNetOpenAuth.OAuth2/OAuth2/ChannelElements/IAuthorizationDescription.cs
+++ b/src/DotNetOpenAuth.OAuth2/OAuth2/ChannelElements/IAuthorizationDescription.cs
@@ -68,11 +68,13 @@ namespace DotNetOpenAuth.OAuth2.ChannelElements {
 		}
 
 		/// <summary>
-		/// Gets the name on the account whose data on the resource server is accessible using this authorization.
+		/// Gets the name on the account whose data on the resource server is accessible using this authorization, if applicable.
 		/// </summary>
+		/// <value>A username, or <c>null</c> if the authorization is to access the client's own data (not a distinct resource owner's data).</value>
 		string IAuthorizationDescription.User {
 			get {
-				Contract.Ensures(!string.IsNullOrEmpty(Contract.Result<string>()));
+				// Null and non-empty are allowed, but not empty.
+				Contract.Ensures(Contract.Result<string>() != String.Empty);
 				throw new NotImplementedException();
 			}
 		}