public ClientPropertiesBuilder setUsingBootstrapControllers(boolean usingBootstrapControllers) {
            this.usingBootstrapControllers = usingBootstrapControllers;
            return this;
        }
Wait for a controller to mark all the brokers as ready (registered and unfenced).
And also wait for the metadata cache up-to-date in each broker server.
core/src/test/java/kafka/testkit/KafkaClusterTestKit.java