A load of Kotlin nullability related warnings + Registrar Java deoprecation when compiling

[MrCsabaToth]

Task :soundpool:compileReleaseKotlin
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (17, 48): 'Registrar' is deprecated. Deprecated in Java
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (32, 37): 'Registrar' is deprecated. Deprecated in Java
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (57, 48): Unchecked cast: Any! to Map<String, Int>
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (77, 48): Unchecked cast: Any! to Map<String, Int>
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (84, 48): Unchecked cast: Any! to Map<String, Any>
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (142, 9): 'constructor SoundPool(Int, Int, Int)' is deprecated. Deprecated in Java
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (173, 56): Unchecked cast: Any! to Map<String, Any>
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (176, 40): 'createTempFile(String = ..., String? = ..., File? = ...): File' is deprecated. Avoid creating temporary files in the default temp location with this function due to too wide permissions on the newly created file. Use kotlin.io.path.createTempFile instead or resort to java.io.File.createTempFile.
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (196, 56): Unchecked cast: Any! to Map<String, Any>
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (204, 56): 'createTempFile(String = ..., String? = ..., File? = ...): File' is deprecated. Avoid creating temporary files in the default temp location with this function due to too wide permissions on the newly created file. Use kotlin.io.path.createTempFile instead or resort to java.io.File.createTempFile.
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (229, 48): Unchecked cast: Any! to Map<String, Any>
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (243, 48): Unchecked cast: Any! to Map<String, Int>
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (253, 48): Unchecked cast: Any! to Map<String, Int>
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (261, 48): Unchecked cast: Any! to Map<String, Int>
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (269, 48): Unchecked cast: Any! to Map<String, Any?>
w: /home/csaba/.pub-cache/hosted/pub.dartlang.org/soundpool-2.3.0/android/src/main/kotlin/pl/ukaszapps/soundpool/SoundpoolPlugin.kt: (291, 48): Unchecked cast: Any! to Map<String, Any?>

I'm using Kotlin version 1.6.21