Fix #842

[IMoHaMeDHaMdYI]

:loudspeaker: Type of change

• [x] Bugfix
• [ ] New feature
• [ ] Enhancement
• [ ] Refactoring

:scroll: Description

Changed MutableList to CopyOnWriteArrayList to prevent ConcurrentModificationException

:bulb: Motivation and Context

I took this class as reference to create an animation to my lists, I had this problem and I wanted to help other people out if they are deciding to use this class in their apps

:green_heart: How did you test it?

I had a case in this gif in the issue #842 and now it doesn't happen

:pencil: Checklist

• [x] I ran ./gradlew spotlessApply before submitting the PR
• [x] I reviewed submitted code
• [ ] I added tests to verify changes
• [x] All tests passing

:camera_flash: Screenshots / GIFs

Look at #842

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[IMoHaMeDHaMdYI]

@googlebot I signed it!

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