14035: Add 'toJson' method to produce expected serialization

Author: sbabcoc

java/src/org/openqa/selenium/Rectangle.java

@@ -17,6 +17,7 @@
 
 package org.openqa.selenium;
 
+import java.util.Map;
 import java.util.Objects;
 
 public class Rectangle {
@@ -64,6 +65,11 @@ public Dimension getDimension() {
     return new Dimension(width, height);
   }
 
+  private Map<String, Object> toJson() {
+    return Map.of("class", getClass().getName(),
+      "width", width, "height", height, "x", x, "y", y);
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) {