How to use the @here/harp-materials.EdgeMaterial.DEFAULT_COLOR_MIX function in @here/harp-materials

private getPolygonFadingParams(
        displayZoomLevel: number,
        technique: FillTechnique | ExtrudedPolygonTechnique
    ): PolygonFadingParameters {
        let color: string | number | undefined;
        let colorMix = EdgeMaterial.DEFAULT_COLOR_MIX;

        if (technique.lineColor !== undefined) {
            color = getPropertyValue(technique.lineColor, displayZoomLevel);
            if (isExtrudedPolygonTechnique(technique)) {
                const extrudedPolygonTechnique = technique as ExtrudedPolygonTechnique;
                colorMix =
                    extrudedPolygonTechnique.lineColorMix !== undefined
                        ? extrudedPolygonTechnique.lineColorMix
                        : EdgeMaterial.DEFAULT_COLOR_MIX;
            }
        }

        const fadeNear =
            technique.fadeNear !== undefined
                ? getPropertyValue(technique.fadeNear, displayZoomLevel)
                : FadingFeature.DEFAULT_FADE_NEAR;

private getPolygonFadingParams(
        displayZoomLevel: number,
        technique: FillTechnique | ExtrudedPolygonTechnique
    ): PolygonFadingParameters {
        let color: string | number | undefined;
        let colorMix = EdgeMaterial.DEFAULT_COLOR_MIX;

        if (technique.lineColor !== undefined) {
            color = getPropertyValue(technique.lineColor, displayZoomLevel);
            if (isExtrudedPolygonTechnique(technique)) {
                const extrudedPolygonTechnique = technique as ExtrudedPolygonTechnique;
                colorMix =
                    extrudedPolygonTechnique.lineColorMix !== undefined
                        ? extrudedPolygonTechnique.lineColorMix
                        : EdgeMaterial.DEFAULT_COLOR_MIX;
            }
        }

        const fadeNear =
            technique.fadeNear !== undefined
                ? getPropertyValue(technique.fadeNear, displayZoomLevel)
                : FadingFeature.DEFAULT_FADE_NEAR;
        const fadeFar =
            technique.fadeFar !== undefined
                ? getPropertyValue(technique.fadeFar, displayZoomLevel)
                : FadingFeature.DEFAULT_FADE_FAR;

        const lineFadeNear =
            technique.lineFadeNear !== undefined
                ? getPropertyValue(technique.lineFadeNear, displayZoomLevel)
                : fadeNear;