public CHAINS getChains() {
        if (chains == null)
            throw new IllegalStateException("Null chains for " + this);
        return chains;
    }
Holder for components and options related to either processing/search/docproc
for a container cluster.

@author gjoranv
config-model/src/main/java/com/yahoo/vespa/model/container/component/ContainerSubsystem.java