Callback for a wait operation.
It should be used as input for EtcdClient.waitForKey.
It contains methods for retrieving an EtcdGetKeyResponse received once a change to etcd is registered.
Future wrapped around the EtcdGetKeyResponse to be returned once the callback is completed.
true if the callback has been completed, false otherwise.
Throwable from an error of an EtcdClient.waitForKey operation.
EtcdGetKeyResponse from etcd sent when a change on a key or directory takes place.