code: function castValue_(key, value) {
    const numProperties = [
      ngeoFormatFeatureProperties.ANGLE,
      ngeoFormatFeatureProperties.OPACITY,
      ngeoFormatFeatureProperties.SIZE,
      ngeoFormatFeatureProperties.STROKE,
      'pointRadius',
      'strokeWidth'
    ];
    const boolProperties = [
      ngeoFormatFeatureProperties.IS_CIRCLE,
      ngeoFormatFeatureProperties.IS_RECTANGLE,
      ngeoFormatFeatureProperties.IS_TEXT,
      ngeoFormatFeatureProperties.SHOW_MEASURE,
      ngeoFormatFeatureProperties.SHOW_LABEL,
      'isCircle',
      'isRectangle',
      'isLabel',
      'showMeasure',
      'showLabel'
    ];
  
    if (numProperties.includes(key)) {
      return +value;
    } else if (boolProperties.includes(key)) {
      return (value === 'true') ? true : false;
    } else {
      return value;
    }
  }
docs: Cast values in the correct type depending on the property.
  @param {string} key Key.
  @param {string} value Value.
  @return {number|boolean|string} The casted value corresponding to the key.
  @private
  @hidden
  @hidden