title: Firestore: Invalid package reference in library
body: <p>After updating to <code>com.google.firebase:firebase-firestore:16.0.0</code> I get the following lint error:</p>
  
  <pre><code>  Error: Invalid package reference in library; not included in Android: javax.naming.directory. Referenced from io.grpc.internal.DnsNameResolver.JndiResolver. [InvalidPackage]
    Error: Invalid package reference in library; not included in Android: javax.naming. Referenced from io.grpc.internal.DnsNameResolver.JndiResolver. [InvalidPackage]
  </code></pre>
  
  <p>Seems that the <code>grpc</code> dependency is making <code>lint</code> unhappy. How can I solve this?</p>