message: More documentation of when to call LoggingActivityContext.enter
diff: # Managing the LoggingActivityContext
  -Backend methods must cooperate to propagate a request's [ActivityId](../../overview/RpcInterface.md#logging-and-activityids) into logging messages. The current ActivityId is held by the [LoggingActivityContext]($common) class. The following rules must be followed in order to manage the state of this context:
  +Asynchronous backend methods must cooperate to propagate a request's [ActivityId](../../overview/RpcInterface.md#logging-and-activityids) into logging messages. The current ActivityId is held by the [LoggingActivityContext]($common) class. The following rules must be followed by async methods to manage this class:
  -Every Promise-returning method:
  -* Must take an argument of type ManagingLoggingActivityContext.md.
  -* Must pass its input LoggingActivityContext object to each Promise-returning method that it calls.
  -* Must call the [LoggingActivityContext.enter]($common) method on its input context object:
  +Every Promise-returning method *must*:
  +* Take an argument of type [LoggingActivityContext]($common).
  +* Pass the input LoggingActivityContext object to each Promise-returning method that it calls.
  +* Call the [LoggingActivityContext.enter]($common) method on the input LoggingActivityContext object:
  * On its first line.
  * Immediately following each call to `await`.
  + * Immediately upon catching an Error thrown by a rejected `await`.
  + * On the first line of a `.then` or a `.catch` callback that is invoked by a Promise.
  -Note that a Promise-returning method is any method that returns a Promise, whether or not it is marked as `async`.
  +Note that a Promise-returning method is any method that returns a Promise, whether or not it is declared with the `async` keyword.
  -There is one exception to the above rule. An [RpcInterface implementation method](../RpcInterface.md#server-implementation) does not take a LoggingActivityContext object as an argument. Instead, it must obtain the LoggingActivityContext by calling [RpcInvocation.current.context]($common). Otherwise, as a Promise-returning function, an RcpInterface implementation method must follow the rules listed above.
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  +There is one exception to the above rule. An [RpcInterface implementation method](../RpcInterface.md#server-implementation) does not take a LoggingActivityContext object as an argument. Instead, it must obtain the LoggingActivityContext by calling [RpcInvocation.current.context]($common). An RcpInterface implementation method must follow all of the other the rules listed above.
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