title: Is there a way to implement map<string, map<string, list<string>>> in protobuf 3?
body: <p>I tried this but have scope issues.</p>
  
  <pre><code>message DataCollectionMessage {
  
      message subData
      {
          message SubDataList {
              repeated string data = 1;
          }
          map&lt;string, subData&gt; parameters = 1;
      }
      map&lt;string,SubDataList&gt; parameters =1;
  }
  </code></pre>
  
  <p>Here SubDataList and subData have unresolved references.</p>