[Fix][Zeta] Signal extends Serializable

Author: nzw921rx

seatunnel-api/src/main/java/org/apache/seatunnel/api/signal/FlushSignal.java

@@ -17,6 +17,13 @@
 
 package org.apache.seatunnel.api.signal;
 
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import lombok.ToString;
+
+@Getter
+@RequiredArgsConstructor
+@ToString
 public final class FlushSignal implements Signal {
 
     private final long jobId;
@@ -26,25 +33,4 @@ public final class FlushSignal implements Signal {
     public static FlushSignal of(long jobId, long taskId) {
         return new FlushSignal(jobId, taskId, System.currentTimeMillis());
     }
-
-    public FlushSignal(long jobId, long taskId, long createdTime) {
-        this.jobId = jobId;
-        this.taskId = taskId;
-        this.createdTime = createdTime;
-    }
-
-    @Override
-    public long getJobId() {
-        return jobId;
-    }
-
-    @Override
-    public long getTaskId() {
-        return taskId;
-    }
-
-    @Override
-    public long getCreatedTime() {
-        return createdTime;
-    }
 }

seatunnel-api/src/main/java/org/apache/seatunnel/api/signal/Signal.java

@@ -17,6 +17,8 @@
 
 package org.apache.seatunnel.api.signal;
 
+import java.io.Serializable;
+
 /**
  * Interface for control-plane signals that the engine propagates through the data flow.
  *
@@ -37,7 +39,7 @@
  * <p>Concrete signals should be small and immutable. New signal types are added by introducing new
  * implementations of this interface; the engine routes them by type via {@code instanceof}.
  */
-public interface Signal {
+public interface Signal extends Serializable {
 
     /** @return the id of the job that created this signal. */
     long getJobId();