8340210: Add positionTestUI() to PassFailJFrame.Builder

Backport-of: f0ae90f30c346544e87217ef1832d6a350fe1985

Author: GoeLin

test/jdk/java/awt/regtesthelpers/PassFailJFrame.java

@@ -1250,6 +1250,29 @@ public Builder testUI(WindowCreator windowCreator) {
             return this;
         }
 
+        /**
+         * Adds an implementation of {@link PositionWindows PositionWindows}
+         * which the framework will use to position multiple test UI windows.
+         *
+         * @param positionWindows an implementation of {@code PositionWindows}
+         *                        to position multiple test UI windows
+         * @return this builder
+         * @throws IllegalArgumentException if the {@code positionWindows}
+         *              parameter is {@code null}
+         * @throws IllegalStateException if the {@code positionWindows} field
+         *              is already set
+         */
+        public Builder positionTestUI(PositionWindows positionWindows) {
+            if (positionWindows == null) {
+                throw new IllegalArgumentException("positionWindows parameter can't be null");
+            }
+            if (this.positionWindows != null) {
+                throw new IllegalStateException("PositionWindows is already set");
+            }
+            this.positionWindows = positionWindows;
+            return this;
+        }
+
         /**
          * Adds a {@code WindowListCreator} which the framework will use
          * to create a list of test UI windows.