zavro.EncodeSchema encodes a Zed record field with the null type as an
Avro union containing "null" twice (i.e., as ["null","null"]), but Avro
unions may not contain more than one unnamed schema of the same type.
Fix this by encoding such field as "null" rather than as a union.
zavro.EncodeSchema encodes a Zed record field with the null type as an Avro union containing "null" twice (i.e., as ["null","null"]), but Avro unions may not contain more than one unnamed schema of the same type. Fix this by encoding such field as "null" rather than as a union.