docs: @Nullable
    public SoyNode firstChildThatMatches(Predicate<SoyNode> condition) {
      int firstChildIndex = 0;
      while (firstChildIndex < numChildren() && !condition.test(getChild(firstChildIndex))) {
        firstChildIndex++;
      }
      if (firstChildIndex < numChildren()) {
        return getChild(firstChildIndex);
      }
      return null;
    }