It should be possible to create a Job Stream without a starter

Current Situation

It is mandatory to asssign a starter to a job stream. When a job stream is shared across different folders then each folder must have a starter to be able to start the part of the job stream in the actual folder.
This is not always wanted. It is sufficient if one part of the job stream has a starter and the other parts will be started by events.

Desired Behavior

It should be possible to create a job stream without a starter. When no starter is defined, instead a connector should be shown. All jobs that have a reference to events that are created from other parts of the job stream located in other folders will be connected to the connector.

It should be possible to delete a starter from a job stream if there is at least one starter for the job stream in another folder. When deleting all starters for a job stream part in a folder then the connector will be displayed instead of the starter and all jobs that use events that are created by parts of the job stream in other folders will be connected.

In addition, starters can be added to job stream parts that have only a connector.

If no job can be connected to the connector (and no starters are defined) then all jobs will be displayed without any connection because the first job is not defined.