Differentiate "displayNameKey" for entities without "referenceDataValue"

Purpose

In order to manage translations on the UI there is a need to differentiate "displayNameKey" for entities without "referenceDataValue". In the example below "displayNameKey" is the same for two records but in the last one, the "referenceDataValue" is present. And for these two cases, the different translation strings should be applied on the UI. A possible solution is for a entity without "displayNameKey" to add at the end of the "displayNameKey" value something like ".no.referrenceData" or something like that to differentiate those two cases, but this should be consistent for such cases.

{
    "fieldId" : "holdings.electronic.access.publicnote",
    "displayNameKey" : "holdings.electronic.access.publicNote",
    "path" : "$.holdings.electronicAccess[?(!(@.relationshipId) || @.relationshipId == null)].publicNote",
    "recordType" : "HOLDINGS"
  }, {
    "fieldId" : "holdings.electronic.access.publicnote.no.display.constant.generated",
    "displayNameKey" : "holdings.electronic.access.publicNote",
    "referenceDataValue" : "No display constant generated",
    "path" : "$.holdings.electronicAccess[?(@.relationshipId==ef03d582-219c-4221-8635-bc92f1107021)].publicNote",
    "recordType" : "HOLDINGS"
  }

Acceptance criteria
1. "displayNameKey" for entities without "referenceDataValue" is not the same as for entities with it. This should handle already merged code and followed for the code which is going be merged.
2. "fieldId" and "displayNameKey" for all entities without "referenceDataValue":

• Instance/Holdings/Item - Electronic access - URI
• Instance/Holdings/Item - Electronic access - Link Text
• Instance/Holdings/Item - Electronic access - Materials specified
• Instance/Holdings/Item - Electronic access - URL Public note

should be with ".default" in the end, for example: "holdings.electronic.access.publicnote.default"