public int compare(Comparable a, Comparable b) {
      return a.compareTo(b);
    }
A map of comparable keys to values. Unlike {@code TreeMap}, this class uses
insertion order for iteration order. Comparison order is only used as an
optimization for efficient insertion and removal.

<p>This implementation was derived from Android 4.1's TreeMap and
LinkedHashMap classes.
lottie/src/main/java/com/airbnb/lottie/parser/moshi/LinkedHashTreeMap.java