code: function updateBranchMetaData(manifest, preferences) {
      let metadatas = manifest.manifest.application[0]["meta-data"] || [];
      const metadata = [];
      const keys = ["io.branch.sdk.BranchKey", "io.branch.sdk.TestMode"];
      const vals = [
        preferences.branchKey,
        preferences.androidTestMode || "false"
      ];
  
      // remove old
      for (var i = 0; i < keys.length; i++) {
        metadatas = removeBasedOnAndroidName(metadatas, keys[i]);
      }
  
      // add new
      for (i = 0; i < keys.length; i++) {
        const key = keys[i];
        const val = vals[i];
        metadata.push({
          $: {
            "android:name": key,
            "android:value": val
          }
        });
      }
      manifest.manifest.application[0]["meta-data"] = metadatas.concat(metadata);
  
      return manifest;
    }
docs: adds to <application> for Branch init and testmode: <meta-data android:name="io.branch.sdk.BranchKey" android:value="key_live_icCccJIpd7GlYY5oOmoEtpafuDiuyXhT" /> <meta-data android:name="io.branch.sdk.TestMode" android:value="false" />