`ExnpandableTextView` doesn't maintain expanded state changes between orientation/config changes

[abbasshah17]

ExnpandableTextView doesn't maintain expanded state changes between orientation/config changes.

How to reproduce:

1. Remove android:configChanges from manifest of current Demo.
2. Run the app.
3. Expand ExpandableTextView.
4. and
5. Change orientation of the device.

ExpandableTextView loses its expanded state.

[abbasshah17]

Added a pull request with a fix.