function optionalColorLike(flatStyle, property) {
  const encoded = flatStyle[property];
  if (encoded === undefined) {
    return undefined;
  }
  return requireColorLike(encoded, property);
}
@param {FlatStyle} flatStyle The flat style.
@param {string} property The symbolizer property.
@return {string|Array<number>|undefined} A string or an array of color values or undefined.