DBZ-8135 InProcessSignalChannel#read() returns empty list when channel is closed

debezium-core/src/main/java/io/debezium/pipeline/signal/channels/process/InProcessSignalChannel.java

@@ -49,6 +49,9 @@ public void init(CommonConnectorConfig connectorConfig) {
 
     @Override
     public List<SignalRecord> read() {
+        if (!open.get()) {
+            return List.of();
+        }
         return Stream.ofNullable(signals.poll()).toList();
     }