Updates the specified AdHoc Group with new data.
Returns the updated group or validation errors.

Required Fields:

• cartId (route) - required
• adhocGroupId (route) - required
• untypedRecord (body) - required

Behavior

• Requires the EnableCartAdhocGroups feature to be enabled; returns 500 with a localized message when disabled.
• Validates the cartId and the AdHoc Group Id format; the group must already be associated with the cart.
• Updatable fields include Name, Sequence, ChargeType, Category, Configuration, Description, Frequency, and GroupType.
• Returns 404 when the group is not associated with the cart or cannot be found after update.