There is a bunch of nonsensical operations registered at the mod_cluster configuration resource, see https://wildscribe.github.io/WildFly/12.0/subsystem/modcluster/mod-cluster-config/configuration/index.html
- add-custom-metric Add new custom metric to the load balancer provider.
- add-metric Add new metric to the load balancer provider.
- remove-custom-metric Remove a custom metric from the load balancer provider.
- remove-metric Remove a metric from the load balancer provider.
These should have been deprecated long time ago, since they are just redundant. Regular model :add/:remove operations should be used for manipulating load metrics.