@RestrictTo(RestrictTo.Scope.LIBRARY)
  public final void setAnimation(@Nullable BaseKeyframeAnimation<?, ?> animation) {
    this.animation = animation;
  }
Override this if you haven't set a static value in the constructor or with setValue.
<p>
Return null to resort to the default value.

Refer to the javadoc for this class for a special case that requires manual invalidation
each time you want to return something different from this method.
lottie/src/main/java/com/airbnb/lottie/value/LottieValueCallback.java