server: unable to read json encoded addenda records

[adamdecaf]

#291 was a discovery (and fix) for being unable to read batches in the JSON structure for an ach.File, but we're also unable to read addenda records.

type EntryDetail struct {
  // ... 
  Addendum []Addendumer `json:"addendum,omitempty"`
}

The problem is that Addendumer is an interface and so encoding/json can't read that into a concrete type. We need to do something similar for addenda records as we did in #292.

Also, the json encoding for addenda records often overlaps. We need to find a unique key to unmarshal into the correct addenda records. Export typeCode?

[adamdecaf]

Slack chat about this: https://moov-io.slack.com/archives/CAH29P84F/p1539032259000100

[bkmoovio]

I don't exactly what you are trying to do but the typeCode has a default value
// NewAddenda02 returns a new Addenda02 with default values for none exported fields
func NewAddenda02() *Addenda02 {
addenda02 := new(Addenda02)
addenda02.recordType = "7"
addenda02.typeCode = "02"
return addenda02
}

How do you handle recordType? Can you do the same?

Dis-regard I modified typeCode to to be exportable.