@Override
    public Optional<String> getPreShutdownCommand() {
        if (flushOnShutdown) {
            int port = getRpcPort();
            String cmd = getDefaults().underVespaHome("bin/vespa-proton-cmd ") + port + " prepareRestart";
            return Optional.of(cmd);
        } else {
            return Optional.empty();
        }
    }
Represents a search node (proton).
<p>
Due to the current disconnect between StorageNode and SearchNode, we have to
duplicate the set of RestartConfigs classes from StorageNode here, as SearchNode
runs in a content/storage node context without this being immediately obvious
in the model.

@author arnej27959
@author hmusum
config-model/src/main/java/com/yahoo/vespa/model/search/SearchNode.java