DeploymentModelUtils is deprecated, telling users to use DeploymentResourceSupport. But DeploymentResourceSupport doesn't provide access to the ManagementResourceRegistration, so there is no replacement for the access available via DeploymentModelUtils.MUTABLE_REGISTRATION_ATTACHMENT.

Use cases I see for accessing the MRR:

1) Adding child registrations with attributes that depend on the deployment specifics. (Driver statistics for ds.xml deployments; JPA provider stats for JPA deployments).

2) Iterating over the deployment tree to find metrics to make available via wildfly-metrics or Micrometer. (This only needs ImmutableManagementResourceRegistration.)