If existing consumers aren't using a mandatory message element, then changing or removing that element need no longer be considered a breaking change.

若现有消费者未用到某必备消息元素，那么修改或去除该元素就不用被看成是一种破坏性变化。

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The mandatory SOAP Body element contains the actual SOAP message.

具有强制性的SOAP主体元素包含了现行的SOAP信息。

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