protected final void set0(int n, Object obj) {
    throwIfImmutable();

    try {
      arr[n] = obj;
    } catch (ArrayIndexOutOfBoundsException ex) {
      // Translate the exception.
      throwIndex(n);
    }
  }
Sets the element at the given index, but without doing any type checks on the element. This
method is protected so that subclasses may offer a safe type-checked public interface to their
clients.

@param n {@code >= 0, < size();} which element
@param obj {@code null-ok;} the value to store
android/android_framework/dex-maker/src/main/java/com/android/dx/util/FixedSizeList.java