@Override
    public String toString() {
        return "type='" + getType() + "', message='" + message + "', services=[" +
                services.stream().
                        map(service -> service.getServiceName() + " '" + service.getConfigId() + "'").
                        collect(Collectors.joining(", ")) + "]";
    }
Class containing the action to be performed on the given services to handle a config change
between the current active vespa model and the next vespa model to prepare.

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