SetUserName
BUrl& SetUserName(const BString& user);
void SetUserName(const BString& username);
void SetUserName(const BString& name);
authentication.SetUserName(fOptUsername);
authentication->SetUserName(fOptUsername);
SetUserName(BString(&authority_c[offset],
request->SetUserName("walter");
url.SetUserName("user");
url.SetUserName("user");