# UNDF: UNDF-2026-000000744
# UNDF: (leave blank)
--- a/okhttp/third_party/okhttp/main/java/io/grpc/okhttp/internal/Util.java
+++ b/okhttp/third_party/okhttp/main/java/io/grpc/okhttp/internal/Util.java
@@ -20,6 +20,7 @@ package io.grpc.okhttp.internal;
 import java.lang.reflect.Array;
 import java.nio.charset.Charset;
 import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.LinkedHashSet;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
@@ -59,13 +60,16 @@ public final class Util {
   /**
    * Returns a list containing containing only elements found in {@code first}  and also in
    * {@code second}. The returned elements are in the same order as in {@code first}.
+   * Previously O(|first|×|second|) nested loop; now O(|first|+|second|) via HashSet.
    */
   private static <T> List<T> intersect(T[] first, T[] second) {
     List<T> result = new ArrayList<>();
-    for (T a : first) {
-      for (T b : second) {
-        if (a.equals(b)) {
-          result.add(b);
-          break;
-        }
-      }
+    // Build a hash-set of second for O(1) membership test.
+    LinkedHashSet<T> secondSet = new LinkedHashSet<>(Arrays.asList(second));
+    for (T a : first) {
+      if (secondSet.contains(a)) {
+        result.add(a);
+      }
     }
     return result;
   }