Represents an event that can return a result.
The type of the result.
The metadata of the event. This can be used to store additional information about the event.
The result of the event.
Gets a metadata value by key.
Gets a metadata value by key or a default value if the value is null.
Gets the result of the event or a default value if the result is null.
Sets a metadata key-value pair.
Sets the result of the event.