[java] Fixes #12442

Author: diemol

java/src/org/openqa/selenium/remote/RemoteWebElement.java

@@ -262,7 +262,10 @@ public boolean equals(Object obj) {
    */
   @Override
   public int hashCode() {
-    return id.hashCode();
+    if (id != null) {
+      return id.hashCode();
+    }
+    return this.hashCode();
   }
 
   /*