AVRO-2921: Typefix avro.tether.util (#1249)
AVRO-2921: Typefix avro.tether.util (#1249)

Add type hints to avro.tether.util
apache/avro,apache/avro,apache/avro,apache/avro,apache/avro,apache/avro,apache/avro,apache/avro,apache/avro,apache/avro,apache/avro,apache/avro