WSO2 App Manager 1.2.0 - How to use custom app properties in ReST APIs

WSO2 App Manager supports defining and using custom properties for app types. In order to add new custom property, the relevant RXT file (registry extension) and couple of other files should be amended. But these custom properties are not marked as 'custom' properties  in any place. Once defined they are treated just like any other another field.  

With the introduction of the new ReST API implementation in App Manager 1.2.0, it was bit of challenging to expose these custom fields through APIs. The new ReST APIs are documented using Swagger. So when the relevant API response models are defined, the custom fields can't be added as named properties since they are dynamic. So the solution is to have a field, which is a Map, to represent the custom properties. And the need of marking custom fields as 'custom' should be addressed too. 

In App Manager, this has been addressed by having another configuration to store the custom properties.

Where is the definitions file

In the registry there are JSON resources which are custom property definitions. There is a definition file per app type.

e.g. Definition file for web apps -  
         /_system/governance/appmgt/applicationdata/custom-property-definitions/webapp.json

What does a definition file look like

As of now the custom property definitions file only has the names of the custom properties.

e.g.
{"customPropertyDefinitions":[{"name":"overview_custom1"}]}

How do I persist these custom properties for an app using the ReST API

The request payload should contain the custom properties as below.

{
  "name": "app1",
  "version": "1.0",
  "isDefaultVersion":true,
  .
  .
  .
  "customProperties":[
    {
       "name":"overview_custom1",
       "value":"custom_property_1"
    }
  ]
}