Why does the RocketMQ Java client SDK let transaction producers and normal producers share the same defaultMQProducerImpl for sending messages, while the Go SDK requires creating two separate defaultMQProducerImpl instances?

在Go版本里面 NewTransactionProducer 和 NewProducer 会创建出2个defaultProducer JAVA 创建一个事务生产者 就可以同时发送普通和事务消息，Go里面非得创建2个这是为啥呢

Start at the Go NewTransactionProducer and NewProducer entry points, then compare the Java transaction producer setup. Trace how each creates and uses defaultProducerImpl, and document the reason for the difference and whether sharing is supported. Done means the behavior and design rationale are clearly explained.

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