- Change the Binder interface to support ConsumerProperties/ProducerProperties beans and subclasses
- Binders can subclass the property beans to add new supported properties that will be automatically populated
- Spring Cloud Stream will infer the target type and populate the beans from the environment based on a `spring.cloud.stream.bindings..<bindingName>` prefix
- Remove binder defaults and retain only general binder configurations
TODO: a) decide on instanceIndex/partitionIndex alignment (we do not need both)
b) support `defaultProducer`/`defaultConsumer` properties
c) add leniency control on binding (fail/ignore for unknown properties)
d) add a `requiredProperties` configuration for consumer/producer properties to finely tune the mandatory properties expected to be supported by a bound application
Changes made during review:
- Add support for consumer and producer defaults
- Remove partitionIndex, keeping only instanceIndex
- Fix default properties for Kafka binder
- Move batching properties to Rabbit only
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