@Override
                                  protected TypeInfo makeInstance(Schema s,
                                      Set<Schema> seenSchemas)
                                      throws AvroSerdeException {
                                    return generateTypeInfoWorker(s, seenSchemas);
                                  }
Generate a list of of TypeInfos from an Avro schema.  This method is
currently public due to some weirdness in deserializing unions, but
will be made private once that is resolved.
@param schema Schema to generate field types for
@param seenSchemas stores schemas processed in the parsing done so far,
        helping to resolve circular references in the schema
@return List of TypeInfos, each element of which is a TypeInfo derived
        from the schema.
@throws AvroSerdeException for problems during conversion.
serde/src/java/org/apache/hadoop/hive/serde2/avro/SchemaToTypeInfo.java