code: public static boolean showInstallPrompt(@NonNull Activity activity, int requestCode) {
          String installReferrerString = "";
          if (Branch.getInstance() != null) {
              JSONObject latestReferringParams = Branch.getInstance().getLatestReferringParams();
              String referringLinkKey = "~" + Defines.Jsonkey.ReferringLink.getKey();
              if (latestReferringParams != null && latestReferringParams.has(referringLinkKey)) {
                  String referringLink = "";
                  try {
                      referringLink = latestReferringParams.getString(referringLinkKey);
                      // Considering the case that url may contain query params with `=` and `&` with it and may cause issue when parsing play store referrer
                      referringLink = URLEncoder.encode(referringLink, "UTF-8");
                  } catch (JSONException | UnsupportedEncodingException e) {
                      e.printStackTrace();
                  }
                  if (!TextUtils.isEmpty(referringLink)) {
                      installReferrerString = Defines.Jsonkey.IsFullAppConv.getKey() + "=true&" + Defines.Jsonkey.ReferringLink.getKey() + "=" + referringLink;
                  }
              }
          }
          return InstantAppUtil.doShowInstallPrompt(activity, requestCode, installReferrerString);
      }
docs: Method shows play store install prompt for the full app. Thi passes the referrer to the installed application. The same deep link params as the instant app are provided to the
  full app up on Branch#initSession()
  
  @param activity    Current activity
  @param requestCode Request code for the activity to receive the result
  @return {@code true} if install prompt is shown to user