Adding additional metadata for properties

The x-gw-sinceExtensionsVersion attribute

Every property can have an x-gw-sinceExtensionsVersion attribute. This is a string value that specifies the first version of the API that included the extension property.

For example, the following specifies that the CustomEntity_Ext entity has an ExpirationDate field that was added in version 1.1.0.
  "definitions": {
    "CustomEntityExt": {
      ...
      "properties": {
        ...
        "expirationDate": {
          "x-gw-sinceExtensionsVersion": "1.1.0"
        }
        ...

There is also an x-gw-sinceVersion used by Guidewire to identify the first version of the API that included a base configuration property.