how to resolve "Username must not be null!" ISSUE

[firethumbs]

I did every thing step by step according to the manual.
I have added gpr.user and gpr.key and generate my account key and token of my github account and added dependencies. but when I built my app I will get this error message.

"Username must not be null!"

Execution failed for task ':app:checkDebugAarMetadata'.

Could not resolve all files for configuration ':app:debugRuntimeClasspath'.
Could not resolve com.cuberto:liquid-swipe:1.0.0.
Required by:
project :app
> Could not resolve com.cuberto:liquid-swipe:1.0.0.
> Could not get resource 'https://maven.pkg.github.com/Cuberto/liquid-swipe-android/com/cuberto/liquid-swipe/1.0.0/liquid-swipe-1.0.0.pom'.
> Username must not be null!

• Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

Best regards