Inconsistent serialization behavior w.r.t java

Test code:

package main

import (
    "fmt"
    "github.com/linkedin/goavro"
)


func main() {
    codec, err := goavro.NewCodec(`
            {
              "type": "record",
              "name": "LongList",
              "fields" : [
      {"name": "foo", "type": "string", "default": "foo"},
      {"name": "bar", "type": "string", "default": "bar"}
              ]
            }`)
    if err != nil {
        fmt.Println(err)
    }

    // NOTE: May omit fields when using default value
    textual := []byte(`{"foo":"foo"}`)

    // Convert textual Avro data (in Avro JSON format) to native Go form
    native, _, err := codec.NativeFromTextual(textual)
    if err != nil {
        fmt.Println(err)
    }

    print(native.(map[string]interface{})["bar"].(string))

}

This code prints bar.

Same test case with java avro-tools fails.

Start with the supplied Go program, especially goavro.NewCodec and NativeFromTextual, using the shown schema and textual input. Compare its handling of the omitted bar field with java avro-tools; done means the implementations agree and the behavior is covered by a regression test.