Defined in github.com/aws/aws-sdk-go/service/swf/api.go
If set, specifies the maximum time before which a worker processing a task of this type must report progress by calling RecordActivityTaskHeartbeat. If the timeout is exceeded, the activity task is automatically timed out. If the worker subsequently attempts to record a heartbeat or returns a result, it will be ignored. This overrides the default heartbeat timeout specified when registering the activity type using RegisterActivityType.
The duration is specified in seconds; an integer greater than or equal to 0. The value "NONE" can be used to specify unlimited duration.