XdsCredentialsRegistry.getProvider(java.lang.String).ChannelCredentials from the given jsonConfig, or
null if the given config is invalid.NettyServerBuilder to allow experimental level
transport-specific configuration.ServerBuilder to create xDS managed servers.XdsServerBuilder.xdsServingStatusListener(XdsServingStatusListener).XdsServerBuilder.XdsServingStatusListener to receive "serving" and "not serving" states.