public ObjectProperty<Color> colorProperty() {
        if (null == color) {
            color = new ObjectPropertyBase<Color>(_color) {
                @Override protected void invalidated() { fireSectionEvent(UPDATE_EVENT); }
                @Override public Object getBean() { return Section.this; }
                @Override public String getName() { return "color"; }
            };
        }
        return color;
    }
Defines the color that will be used to colorize the section in
a gauge.
@param COLOR
src/main/java/eu/hansolo/tilesfx/Section.java