code: public java.lang.String getVersionUrl() {
      java.lang.Object ref = versionUrl_;
      if (ref instanceof java.lang.String) {
        return (java.lang.String) ref;
      } else {
        com.google.protobuf.ByteString bs = 
            (com.google.protobuf.ByteString) ref;
        java.lang.String s = bs.toStringUtf8();
        versionUrl_ = s;
        return s;
      }
    }
docs: <pre>
  Serving URL for this version. Example:
  "https://myversion-dot-myservice-dot-myapp.appspot.com"
  &#64;OutputOnly
  </pre>
  
  <code>string version_url = 109;</code>