内置通道

¥Built-in Channels

虽然 diagnostics_channel API 现在被认为是稳定的，但当前可用的内置通道却不稳定。每个通道都必须独立声明为稳定的。

¥While the diagnostics_channel API is now considered stable, the built-in channels currently available are not. Each channel must be declared stable independently.