Required Fields:

• businessObjectId (route) - required
• type (query) - required; e.g. Proposal, Collaboration Request, Order, Agreement

Returns the most recently activated cart for the specified business object in a read-only view.
This endpoint does not create, modify, or activate a cart; it is a lookup that never mutates state.
Requirements

• businessObjectId (route): required; must be a valid GUID.

• type (query): required; the business object type (e.g., Proposal, Collaboration Request, Order, Agreement).

• When the business-object-agnostic cart service is disabled, only "Proposal" and "Collaboration Request" types are supported.
  Behavior

• Queries carts by BusinessObjectId and BusinessObjectType, excluding carts in Abandoned status.

• Orders results by ActivationDate descending and selects the first (latest) cart.

• Adds IsReadonly=true to the cart's CustomProperties before returning.

• Returns 204 No Content when no matching cart exists (no exception is thrown).
  Processing Order

1. Validate businessObjectId (GUID) and business object type.
2. Query the latest non-Abandoned cart for the business object.
3. Flag the cart as read-only and return it, or return 204 when none is found.