com.onesignal.unity.android/Editor/OneSignalAndroidDependencies.xml

OneSignal is the market leader in customer engagement, powering mobile push, web push, email, and in-app messages.

<dependencies>
  <androidPackages>
    <repositories>
      <repository>https://repo.maven.apache.org/maven2</repository>
    </repositories>
    <androidPackage spec="com.onesignal:OneSignal:5.1.26" />
  </androidPackages>
</dependencies>