src/java.base/share/classes/java/time/zone/ZoneOffsetTransition.java

*** 102,111 ****
--- 102,115 ----
      /**
       * Serialization version.
       */
      private static final long serialVersionUID = -6946044323557704546L;
      /**
+      * The transition epoch-second.
+      */
+     private final long epochSecond;
+     /**
       * The local transition date-time at the transition.
       */
      private final LocalDateTime transition;
      /**
       * The offset before transition.
*** 150,159 ****
--- 154,164 ----
       * @param transition  the transition date-time with the offset before the transition, not null
       * @param offsetBefore  the offset before the transition, not null
       * @param offsetAfter  the offset at and after the transition, not null
       */
      ZoneOffsetTransition(LocalDateTime transition, ZoneOffset offsetBefore, ZoneOffset offsetAfter) {
+         this.epochSecond = transition.toEpochSecond(offsetBefore);
          this.transition = transition;
          this.offsetBefore = offsetBefore;
          this.offsetAfter = offsetAfter;
      }
  
*** 163,172 ****
--- 168,178 ----
       * @param epochSecond  the transition epoch-second
       * @param offsetBefore  the offset before the transition, not null
       * @param offsetAfter  the offset at and after the transition, not null
       */
      ZoneOffsetTransition(long epochSecond, ZoneOffset offsetBefore, ZoneOffset offsetAfter) {
+         this.epochSecond = epochSecond;
          this.transition = LocalDateTime.ofEpochSecond(epochSecond, 0, offsetBefore);
          this.offsetBefore = offsetBefore;
          this.offsetAfter = offsetAfter;
      }
  
*** 207,217 ****
       *
       * @param out  the output stream, not null
       * @throws IOException if an error occurs
       */
      void writeExternal(DataOutput out) throws IOException {
!         Ser.writeEpochSec(toEpochSecond(), out);
          Ser.writeOffset(offsetBefore, out);
          Ser.writeOffset(offsetAfter, out);
      }
  
      /**
--- 213,223 ----
       *
       * @param out  the output stream, not null
       * @throws IOException if an error occurs
       */
      void writeExternal(DataOutput out) throws IOException {
!         Ser.writeEpochSec(epochSecond, out);
          Ser.writeOffset(offsetBefore, out);
          Ser.writeOffset(offsetAfter, out);
      }
  
      /**
*** 251,261 ****
       * Gets the transition instant as an epoch second.
       *
       * @return the transition epoch second
       */
      public long toEpochSecond() {
!         return transition.toEpochSecond(offsetBefore);
      }
  
      //-------------------------------------------------------------------------
      /**
       * Gets the local transition date-time, as would be expressed with the 'before' offset.
--- 257,267 ----
       * Gets the transition instant as an epoch second.
       *
       * @return the transition epoch second
       */
      public long toEpochSecond() {
!         return epochSecond;
      }
  
      //-------------------------------------------------------------------------
      /**
       * Gets the local transition date-time, as would be expressed with the 'before' offset.