start
Starts the server, initializing any necessary resources and beginning to listen for incoming client connections or events.
This method ensures that the server transitions into a running state, allowing it to process incoming messages, send SSE events FeatureMessage, and respond to health check requests from clients.
It is recommended to check the server's state using isStarted before invoking this method to prevent redundant operations.
Throws
if the server is already running or cannot be started due to invalid configuration.
IOException
if an error occurs while initializing the server's underlying infrastructure.