Sidecar message consumption AVRO deserialization assumes records

[jlrobins]

Avro can serialize lots of toplevel things that are NOT records (primitives, etc.), but RecordDeserializer.java::handleAvro() assumes Record, and croaks when deserializing, say, a key schema describing "just a long encoding of a timestatmp", used as key schema of topic WeatherData within our test custom data cluster.

Schema WeatherData-key:

{
  "logicalType": "timestamp-micros",
  "type": "long"
}

The exception raised:

....
Caused by: java.lang.ClassCastException: java.lang.Long cannot be cast to org.apache.avro.generic.GenericData$Record
at io.confluent.idesidecar.restapi.messageviewer.RecordDeserializer.handleAvro(RecordDeserializer.java:134)
...

Enums, Arrays, Maps, Fixed, and primitives could all be the toplevel type, not just Records, and will probably deserialize to distinct java-side classes, not GenericData.Record.

It does not appear to me that JSONSchema or Protobuf will have the same weakness:

1. As far as I can see, Protobuf messages are always the equivalent of a record, perhaps though just encapsulating a single field.
2. Despite JSON being similar to Avro in allowing toplevel primitives and arrays (not objects), the deserialization code in sidecar treats as a JsonNode only, which will handle all.