message: In-app messages - allow showing the message for chosen platforms only (lib)
diff: @@ -1615,13 +1615,16 @@ error Context::fetchMessage(const bool periodic) {
  !root.isMember("title") ||
  !root.isMember("text") ||
  !root.isMember("button") ||
  - !root.isMember("url-mac") ||
  - !root.isMember("url-win") ||
  - !root.isMember("url-linux")) {
  + (!root.isMember("url-mac") && !root.isMember("url-win") && !root.isMember("url-linux"))) {
  logger.debug("Required fields are missing in in-app message JSON");
  return noError;
  }
  + if (!root.isMember("url-" + shortOSName()) {
  + logger.debug("URL not defined for the platform " + shortOSName() + ", will not show the message");
  + return noError;
  + }
  +
  auto messageID = root["id"].asInt64();
  auto type = root["type"].asInt64();
  appversion = root["appversion"].asString();
  