If a binding is applied to a workload, and then the mapping definition for the binding changes, we cannot reliably use the current mapping to remove the projection. Currently the projector always uses the latest mapping definition for projection and unprojection.

From the spec:

When a service binding projection is removed, the controller MUST use the same mappings from the projection creation. After a ClusterWorkloadResourceMapping resource is modified, each binding targeting the mapped workload type MUST be removed, then reattempted with the latest mapping.

This requirement was added to the spec in servicebinding/spec#199, after the projector was written, but before 1.0.

We need to preserve the mapping used to make the projection on the workload so we the know we can unproject at any point in the future. One possibility is to encode the mapping as an annotation on the workload during projection, and look for that annotation during unprojection.