remove unused method

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

app/src/main/java/com/nextcloud/talk/users/UserManager.kt

@@ -25,7 +25,6 @@ import android.text.TextUtils
 import com.bluelinelabs.logansquare.LoganSquare
 import com.nextcloud.talk.data.user.UsersRepository
 import com.nextcloud.talk.data.user.model.User
-import com.nextcloud.talk.data.user.model.UserEntity
 import com.nextcloud.talk.models.ExternalSignalingServer
 import com.nextcloud.talk.models.json.capabilities.Capabilities
 import com.nextcloud.talk.models.json.push.PushConfigurationState
@@ -194,14 +193,6 @@ class UserManager internal constructor(private val userRepository: UsersReposito
         return user
     }
 
-    private fun validDisplayName(displayName: String?, user: UserEntity): Boolean {
-        return if (displayName == null) {
-            false
-        } else {
-            user.displayName == null || user.displayName != null && displayName != user.displayName
-        }
-    }
-
     companion object {
         const val TAG = "UserManager"
     }