Summary

Revert an erroneous change to the serialized format of LinkedHashMap.

Problem

A new field putMode had been added to LinkedHashMap in the initial Sequenced Collection implementation (JDK-8266571). Since the class is serializable, this resulted in an unintended change to the serial format.

Solution

The field should be marked transient to restore the previous serial format.

Specification

@@ -330,7 +330,7 @@ public class LinkedHashMap<K,V>
     static final int PUT_NORM = 0;
     static final int PUT_FIRST = 1;
     static final int PUT_LAST = 2;
-    int putMode = PUT_NORM;
+    transient int putMode = PUT_NORM;

     // Called after update, but not after insertion
     void afterNodeAccess(Node<K,V> e) {

(This has the effect of removing the putMode field from the serialized form of LinkedHashMap as documented on the serialized-form.html page of the specification.)