public String getVersionComment() returns the comment
      provided for this version of the document.
    Parameters
None
Returns
Returns a String representing the version label of the document.
Example
    Document doc = getTestDocument(session);
    
    Log.d(TAG, "getContentStreamLength: " + doc.getContentStreamLength());
    Log.d(TAG, "getContentStreamMimeType: " + doc.getContentStreamMimeType());
    Log.d(TAG, "getVersionComment: " + doc.getVersionComment());
    Log.d(TAG, "getVersionLabel: " + doc.getVersionLabel());
    Log.d(TAG, "isLatestVersion: " + doc.isLatestVersion());
      
      Would result in the following output: