title: Protocol message end-group tag did not match expected tag
body: <p>I keep getting the following stack trace and am not sure what it means. </p>
  
  <pre><code>Caused by: com.google.protobuf.InvalidProtocolBufferException: Protocol message end-group tag did not match expected tag.
      at com.google.protobuf.InvalidProtocolBufferException.invalidEndTag(InvalidProtocolBufferException.java:73)
      at com.google.protobuf.CodedInputStream.checkLastTagWas(CodedInputStream.java:124)
      at com.google.protobuf.AbstractMessageLite$Builder.mergeFrom(AbstractMessageLite.java:189)
      at com.google.protobuf.AbstractMessage$Builder.mergeFrom(AbstractMessage.java:732)
      at com.google.protobuf.AbstractMessage$Builder.mergeFrom(AbstractMessage.java:238)
      at com.google.protobuf.AbstractMessageLite$Builder.mergeFrom(AbstractMessageLite.java:178)
      at com.google.protobuf.AbstractMessage$Builder.mergeFrom(AbstractMessage.java:724)
  </code></pre>
  
  <ul>
  <li>What does "Protocol message end-group tag did not match expected tag." mean? </li>
  <li>What is a "message end-group tag"?</li>
  <li>Is this documented somewhere?</li>
  </ul>