Build errors

[Z6P0]

/opt/flutter/.pub-cache/hosted/pub.dartlang.org/kropper-0.0.2/android/src/main/java/com/kandroid/kropper/PermissionManager.java:5: error: cannot find symbol
import android.support.v4.app.ActivityCompat;
^
symbol: class ActivityCompat
location: package android.support.v4.app
/opt/flutter/.pub-cache/hosted/pub.dartlang.org/kropper-0.0.2/android/src/main/java/com/kandroid/kropper/PermissionManager.java:15: error: cannot find symbol
return ActivityCompat.checkSelfPermission(activity, permissionName)
^
symbol: variable ActivityCompat
location: class PermissionManager
/opt/flutter/.pub-cache/hosted/pub.dartlang.org/kropper-0.0.2/android/src/main/java/com/kandroid/kropper/PermissionManager.java:20: error: cannot find symbol
ActivityCompat.requestPermissions(activity, new String[] {permissionName}, requestCode);
^
symbol: variable ActivityCompat
location: class PermissionManager
3 errors