fix equality

Author: ChrisHegarty

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plan/logical/Merge.java

@@ -45,7 +45,7 @@ public boolean expressionsResolved() {
 
     @Override
     public int hashCode() {
-        return Objects.hash(source().hashCode(), subPlans);
+        return Objects.hash(subPlans);
     }
 
     @Override
@@ -57,8 +57,7 @@ public boolean equals(Object o) {
             return false;
         }
         Merge other = (Merge) o;
-
-        return Objects.equals(source(), other.source()) && Objects.equals(subPlans, other.subPlans);
+        return Objects.equals(subPlans, other.subPlans);
     }
 
     @Override

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plan/physical/MergeExec.java

@@ -80,14 +80,14 @@ public List<? extends PhysicalPlan> subPlans() {
 
     @Override
     public int hashCode() {
-        return Objects.hash(source().hashCode(), physSubPlans);
+        return Objects.hash(physSubPlans);
     }
 
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
         MergeExec other = (MergeExec) o;
-        return Objects.equals(this.source(), other.source()) && Objects.equals(this.physSubPlans, other.physSubPlans);
+        return Objects.equals(this.physSubPlans, other.physSubPlans);
     }
 }