private String toJson(Object obj)
    throws Exception
  {
    ObjectMapper mapper = new ObjectMapper();
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    mapper.writeValue(out, obj);
    return out.toString();
  }
TestDesc - Test the desc objects that are correctly converted to
and from json.  This also sets every field of the TableDesc object.
hcatalog/webhcat/svr/src/test/java/org/apache/hive/hcatalog/templeton/TestDesc.java