title: How to set a seperate bootstrap server to a DLT of a binding
body: <p>I need to send consumed invalid messages into a DLT but in a separate bootstrap server. I currently have this config:</p>
  <pre><code>spring.cloud.stream.binders.some-kafka-binder.type=kafka
  spring.cloud.stream.binders.some-kafka-binder.environment.spring.cloud.stream.kafka.binder.brokers=localhost:29092
  
  spring.cloud.stream.bindings.processor-in-0.binder=some-kafka-binder
  spring.cloud.stream.bindings.processor-in-0.group=${spring.application.name}
  spring.cloud.stream.bindings.processor-in-0.destination=outbound-topic
  spring.cloud.stream.kafka.bindings.processor-in-0.consumer.configuration.value.deserializer=io.confluent.kafka.serializers.KafkaAvroDeserializer
  spring.cloud.stream.kafka.bindings.processor-in-0.consumer.configuration.schema.registry.url=${schema.registry.url}
  spring.cloud.stream.kafka.bindings.processor-in-0.consumer.configuration.specific.avro.reader=true
  spring.cloud.stream.kafka.bindings.processor-in-0.consumer.enable-dlq=true
  spring.cloud.stream.kafka.bindings.processor-in-0.consumer.dlq-name=outbound-topic.DLT
  spring.cloud.stream.kafka.bindings.processor-in-0.consumer.dlq-producer-properties.configuration.value.serializer=io.confluent.kafka.serializers.KafkaAvroSerializer
  spring.cloud.stream.kafka.bindings.processor-in-0.consumer.dlq-producer-properties.configuration.schema.registry.url=${schema.registry.url}
  spring.cloud.stream.kafka.bindings.processor-in-0.consumer.dlq-producer-properties.configuration.bootstrap.servers=localhost:9092
  </code></pre>
  <p>...but I'm getting this error:</p>
  <pre><code>Caused by: java.lang.IllegalStateException: bootstrap.servers cannot be overridden at the binding level; use multiple binders instead
          at org.springframework.util.Assert.state(Assert.java:76)
          at org.springframework.cloud.stream.binder.kafka.KafkaMessageChannelBinder.getProducerFactory(KafkaMessageChannelBinder.java:560)
          at org.springframework.cloud.stream.binder.kafka.KafkaMessageChannelBinder.getErrorMessageHandler(KafkaMessageChannelBinder.java:1148)
          at org.springframework.cloud.stream.binder.kafka.KafkaMessageChannelBinder.getErrorMessageHandler(KafkaMessageChannelBinder.java:158)
          at org.springframework.cloud.stream.binder.AbstractMessageChannelBinder.registerErrorInfrastructure(AbstractMessageChannelBinder.java:695)
          at org.springframework.cloud.stream.binder.AbstractMessageChannelBinder.registerErrorInfrastructure(AbstractMessageChannelBinder.java:639)
          at org.springframework.cloud.stream.binder.kafka.KafkaMessageChannelBinder.createConsumerEndpoint(KafkaMessageChannelBinder.java:734)
          at org.springframework.cloud.stream.binder.kafka.KafkaMessageChannelBinder.createConsumerEndpoint(KafkaMessageChannelBinder.java:158)
          at org.springframework.cloud.stream.binder.AbstractMessageChannelBinder.doBindConsumer(AbstractMessageChannelBinder.java:408)
          ... 27 common frames omitted
  </code></pre>
  <p>Is there a way in spring cloud I can set this up? I really wish that there's no need for me to do a custom DLT implementation.</p>
  <p>If ever you're asking why there's a need for another bootstrap setup for the DLT: there are 2 separate AWS KMS accounts involve.</p>