var config = new ConsumerConfig { BootstrapServers = "localhost:9092", GroupId = "my-group-id", }; var builder = new ConsumerBuilderIn this example, we're using the ConsumerBuilder class to create a Kafka consumer that consumes messages with key of type 'Ignore' (which means we're ignoring the key), and value of type 'string'. We're then setting a custom key deserializer using the SetKeyDeserializer method, passing in an instance of the 'MyCustomKeyDeserializer' class. The package library for the ConsumerBuilder class is the Confluent.Kafka package.(config) .SetKeyDeserializer(new MyCustomKeyDeserializer()); using var consumer = builder.Build(); consumer.Subscribe("my-topic"); while (true) { var result = consumer.Consume(); Console.WriteLine($"Received message with key '{result.Message.Key}' and value '{result.Message.Value}'"); }