if (textAnchor == null) {
            throw new IllegalArgumentException("Null 'textAnchor' argument.");
        }
        if (rotationAnchor == null) {
            throw new IllegalArgumentException(
                "Null 'rotationAnchor' argument."
            );   
        }
        this.text = text;
        this.textAnchor = textAnchor;
        this.rotationAnchor = rotationAnchor;
        this.angle = angle;