Question: Record "com.epiphany.avro.data" field "thumbnailUrl": default value ought to encode using field schema: cannot encode binary bytes: expected: string; received: <nil>]

[smeadows-abb]

I have 3 optional "string" data elements within my json, the following excerpt shows these fields from AVRO schema defines, during compilation I receive " cannot encode binary bytes: expected: string; received: ". I'm unsure how these field should be defined:
CODE:
codec, err := goavro.NewCodec(EntityMap.Schema)
if err != nil {
logger.Warning("schemaID=" + EntityMap.GUID + " " + err.Error())
return err
}
_, _, err = codec.NativeFromTextual(message)
if err != nil {
logger.Warning("schemaID=" + EntityMap.GUID + " " + err.Error())
return err
}
AVRO:
{
"name": "thumbnailUrl",
"type": ["null", "string"],
"default": null
},

      {
        "name": "shortDescription",
        "type": ["null", "string"],
        "default": null
      },

      {
        "name": "longDescription",
        "type": ["null", "string"],
        "default": null
      },