docs: public List<Plugin> plugins(PluginTarget target) {
          switch (requireNonNull(target, "target")) {
              case LEADER_ONLY:
                  return pluginsForLeaderOnly != null ? ImmutableList.copyOf(pluginsForLeaderOnly.plugins())
                                                      : ImmutableList.of();
              case ALL_REPLICAS:
                  return pluginsForAllReplicas != null ? ImmutableList.copyOf(pluginsForAllReplicas.plugins())
                                                       : ImmutableList.of();
              default:
                  // Should not reach here.
                  throw new Error("Unknown plugin target: " + target);
          }
      }