c# - NullReferenceException in SharpSvn's SvnClient when the supplied DefaultCredentials returns null -

i'm using sharpsvn in project communicate svn. svn repostories, know user name , password, while others, don't. thus, set svnclient.authentication.defaultcredentials property instance of own implementation of system.net.icredentials (pseudo code):

public class mycredentials : icredentials {     public networkcredential getcredential(uri uri, string authtype)     {         if (arecredentialsknown(uri))             return new networkcredential("knownusername", "knownpassword");         else             return null;     } } 

this works fine known credentials. however, if credentials not known, nullreferenceexception occurs in sharpsvn:

object reference not set instance of object.    @ system.net.networkcredential.internalgetusername()    @ system.net.networkcredential.get_username()    @ sharpsvn.implementation.svncredentialwrapper.onusernamepassword(object sender, svnusernamepasswordeventargs e) in f:\qqn\sharpsvn-dist-1.6\src\sharpsvn\svnauthentication.h:line 619 

this apparently caused fact return null getcredential method. however, stated the msdn documentation on icredentials interface:

the getcredential method returns networkcredential instance contains credentials associated specified uri , authorization scheme. when no credentials available, getcredential method returns null.

is bug in sharpsvn? otherwise, supposed return when credentials not known?

edit: discovered can return new networkcredentials() instead of null indicate sharpsvn credentials unknown. still, think bug in sharpsvn returning null should work equally well.

the .defaultcredentials alternative providing 1 explicit username , password subversion libraries.

if need more advanced prompting mechanism should hook .usernamepassword event on svnclient.autorization. allows managing if passwords should saved, etc.

there default implementation in sharpsvn.ui.dll hooks standard dialogs.