arbitrary JSON pattern/anti-pattern

[baywet]

Context
Graph.Json is used to model properties or payload of which the shape is unknown.
This makes it really difficult for clients to do anything useful with it.
The vast majority of use is from Excel, and this is historical because they are generating their REST API and CSDL from the object model in the product.

Decision
Graph.Json should not be used anymore, and we'll investigate to replace it by Edm.Untyped instead which is part of Odata. (need to check whether this impact the payload, or internal mechanics of AGS)
Edm.Untyped should ONLY be used in the scenario where the payload/property value comes from outside of the workload and its shape varies/is unknown. (a good example is the SharePoint Pages APIs, webparts can be defined by 3rd parties, and the shape of the webpart properties is unknown by API publishers)