The endpoint configuration contains all the information needed during the handshake process for this end point. All
endpoints specify, for example, a URI. In the case of a server endpoint, the URI signifies the URI to which the
endpoint will be mapped. In the case of a client application the URI signifies the URI of the server to which the
client endpoint will attempt to connect.
Return the Decoder implementation classes configured. These will be instantiated by the container to decode
incoming messages into the expected custom objects on MessageHandler.Whole.onMessage(Object) callbacks.
the decoder implementation classes, the empty list if none.
This method returns a modifiable Map that the developer may use to store application specific information
relating to the endpoint that uses this configuration instance. Web socket applications running on distributed
implementations of the web container should make any application specific objects stored here
java.io.Serializable, or the object may not be recreated after a failover.