private void invalid(StringBuilder changes, ClusterSpec cluster, ChangeContext context) {
        changes.setLength(changes.length() - 2); // Remove last ", "
        context.invalid(ValidationId.resourcesReduction,
                        "Effective resource reduction in " + cluster.id() + " is too large: " +
                        changes +
                        ". To protect against mistakes, changes causing load increases of more than 100% are blocked");
    }
Checks that resources per document per node is reduced too much in one go.

@author bratseth
config-model/src/main/java/com/yahoo/vespa/model/application/validation/change/ResourcesReductionValidator.java