Need update for androidx

[XCarbone]

In PdfDocument.java you use import android.support.v4.util.ArrayMap;
But with the new update android has migrated to androidx and this make the application crash.

Here is the error:
The given artifact contains a string literal with a package reference 'android.support.v4.widget' that cannot be safely rewritten. Libraries using reflection such as annotation processors need to be updated manually to add support for androidx.

[johngray1965]

I wrote a new version: https://github.com/johngray1965/PdfiumAndroidKt
Its modern.