incoming
An incoming Server-Sent Events (SSE) flow.
Each ServerSentEvent can contain following fields:
ServerSentEvent.data data field of the event.
ServerSentEvent.event string identifying the type of event.
ServerSentEvent.id event ID.
ServerSentEvent.retry reconnection time, in milliseconds to wait before reconnecting.
ServerSentEvent.comments comment lines starting with a ':' character.