11.15. Migrating from Anjay 3.11 or 3.12
11.15.1. Addition of resource_instance_remove handler
LwM2M TS 1.2 introduced possibility to delete a Resource Instance, so one additional data model handler had to be added.
New resource_instance_remove handler (and its associated
anjay_dm_resource_instance_remove_t function type) has been introduced. It
is analogous to the instance_remove handler; its job is to remove a specific
Resource Instance from a multiple-instance Resource.
Its implementation is required in objects that include at least one writeable multiple-instance Resource, if the client application aims for compliance with LwM2M 1.2.