name vs. fullname in JSON encoding of union

The JSON Encoding section of the Avro specification states that a union with a non-null value "is encoded as a JSON object with one name/value pair whose name is the type’s name and whose value is the recursively encoded value. For Avro’s named types (record, fixed or enum) the user-specified name is used, for other types the type name is used." This refers to the name, but at least the JSON encoder for Java writes the fullname of the type instead. The terms "name" and "fullname" are defined in Names.

Tasks in this issue:

• Collect information about each implementation: whether its JSON encoder writes the name or the fullname, and whether its JSON decoder accepts the name, fullname, or both.
• Decide whether the name or the fullname should be used.
• Change the specification and implementations according to the decision, or file separate issues for individual implementations.