Android Question Android X Notification Error

[Multiverse app]

I Followed this tutorial about Android X.
After using Jetifier, I'm getting the following error:

B4A Version: 9.30
Java Version: 8
Parsing code.    (0.20s)
Building folders structure.    (0.01s)
Compiling code.    (0.45s)
    
ObfuscatorMap.txt file created in Objects folder.
Compiling layouts code.    (0.05s)
Organizing libraries.    (0.00s)
    (AndroidX SDK)
Generating R file.    (2.53s)
Compiling generated Java code.    Error
B4A line: 135
Dim jo As JavaObject = nb
javac 1.8.0_181
src\com\multiverse\memegenerator\indian\firebasemessaging.java:494: error: cannot access NotificationCompat
_jo.setObject((java.lang.Object)(_nb.getObject()));
                                              ^
  class file for android.support.v4.app.NotificationCompat not found

The Code is for posting Notification:

    '+++++++++++++++++++++++++
        Dim sound As Boolean=True
        Dim p As Phone
        If p.SdkVersion >= 26 Then
            Dim ctxt As JavaObject
            ctxt.InitializeContext
            Dim manager As JavaObject
            manager.InitializeStatic("android.app.NotificationManager")
            Dim Channel As JavaObject
            Dim importance As String
            If sound Then importance = "IMPORTANCE_DEFAULT" Else importance = "IMPORTANCE_LOW"
            Dim ChannelVisibleName As String = Application.LabelName
            Channel.InitializeNewInstance("android.app.NotificationChannel", _
                   Array("MyChannelId1", ChannelVisibleName, manager.GetField(importance)))
            manager = ctxt.RunMethod("getSystemService", Array("notification"))
            manager.RunMethod("createNotificationChannel", Array(Channel))
            Dim jo As JavaObject = nb
            jo.RunMethod("setChannelId", Array("MyChannelId1"))
        End If
    '+++++++++++++++++++++++++

I have already confirmed my Additional libraries folder is not in ProgramFiles, it's located under C:\B4A
These are my imports:

 

[DonManfred]

try to add

#additionallib: androidx.core.app.NotificationCompat

 

[Erel]

What is nb?

 

[Multiverse app]

try to add

#additionallib: androidx.core.app.NotificationCompat

It gives Attribute not supported: additionallib

 

[Multiverse app]

What is nb?

It is a NotificationBuilder object, I'm using your code from here

 

[Erel]

It is a NotificationBuilder object, I'm using your code from here

See the very first sentence. This code is not needed.