@Override
  public ObjectInspector getObjectInspector() throws SerDeException {
    return oi;
  }
Attempt to determine the schema via the usual means, but do not throw
an exception if we fail.  Instead, signal failure via a special
schema.  This is used because Hive calls init on the serde during
any call, including calls to update the serde properties, meaning
if the serde is in a bad state, there is no way to update that state.
serde/src/java/org/apache/hadoop/hive/serde2/avro/AvroSerDe.java