[BEAM-32] Consider not emitting empty ON_TIME pane unless requested

• Type: New Feature
• Status: Resolved
• Priority: P3
• Resolution: Won't Fix
• Fix Version/s: Not applicable
• Component/s: beam-model, runner-core
• Labels: Triggers Windowing backward-incompatible
• Assignee: Kenneth Knowles
• Reporter: Kenneth Knowles
• Created: 19/Feb/16 22:31
• Updated: 24/Jul/20 20:52
• Resolved: 20/Jun/17 18:18

Description

Today, the ReduceFnRunner sets a timers and emits an empty ON_TIME pane as long as the trigger allows it. This could be controlled in a manner analogous to the empty final pane at window expiration (also owned by the ReduceFnRunner).