Entire event would be sent to each route in parallel.
Scatter-Gather works as follows :
- The Scatter-Gather component receives a Mule event and sends a reference of this Mule event to each processing route.
- Each of the processing routes starts executing in parallel. After all processors inside a route finish processing, the route returns a Mule event, which can be either the same Mule event without modifications or a new Mule event created by the processors in the route as a result of the modifications applied.
- After all processing routes have finished execution, the Scatter-Gather component creates a new Mule event that combines all resulting Mule events from each route, and then passes the new Mule event to the next component in the flow.

URL parameters are always accessed using { } like => {customerID}

APIKIt Creates a separate flow for each HTTP method. Hence 4 private flows would be generated.
MuleSoft Documentation Referrence : https://docs.mulesoft.com/mule-runtime/4.3/build-application-from-api