upd

Author: idegtiarenko

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/tree/Node.java

@@ -69,7 +69,7 @@ public void forEachDown(Consumer<? super T> action) {
         action.accept((T) this);
         // please do not refactor it to a for-each loop
         // to avoid allocating iterator that performs concurrent modification checks
-        for (int c = 0; c < children.size(); c++) {
+        for (int c = 0, size = children.size(); c < size; c++) {
             children.get(c).forEachDown(action);
         }
     }
@@ -87,7 +87,7 @@ public <E extends T> void forEachDown(Class<E> typeToken, Consumer<? super E> ac
     public void forEachUp(Consumer<? super T> action) {
         // please do not refactor it to a for-each loop
         // to avoid allocating iterator that performs concurrent modification checks
-        for (int c = 0; c < children.size(); c++) {
+        for (int c = 0, size = children.size(); c < size; c++) {
             children.get(c).forEachUp(action);
         }
         action.accept((T) this);

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

@@ -16,6 +16,7 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.Set;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
@@ -145,7 +146,7 @@ private static Object doTransformExpression(Object arg, Function<Expression, ? e
             boolean hasChanged = false;
             // please do not refactor it to a for-each loop
             // to avoid allocating iterator that performs concurrent modification checks
-            for (int i = 0; i < c.size(); i++) {
+            for (int i = 0, size = c.size(); i < size; i++) {
                 var e = c.get(i);
                 Object next = doTransformExpression(e, traversal);
                 if (e.equals(next) == false) {
@@ -159,6 +160,7 @@ private static Object doTransformExpression(Object arg, Function<Expression, ? e
 
             return hasChanged ? transformed : arg;
         }
+        assert arg instanceof Set<?> == false : "Set arguments are not supported";
 
         return arg;
     }