Fix the time overlap right boundary being included in the overlap (#404)

Fixes #403
Fixes #399

Author: dkhalanskyjb

core/common/test/TimeZoneTest.kt

@@ -281,6 +281,7 @@ private fun checkOverlap(timeZone: TimeZone, overlapStart: LocalDateTime) {
     val instantStart = overlapStart.plusNominalSeconds(-1).toInstant(timeZone).plus(1, DateTimeUnit.SECOND)
     // the later occurrence of the overlap
     val instantEnd = overlapStart.plusNominalSeconds(1).toInstant(timeZone).minus(1, DateTimeUnit.SECOND)
+    assertEquals(instantEnd, overlapStart.toInstant(timeZone))
     try {
         // there is at least a one-second overlap
         assertNotEquals(instantStart, instantEnd)

core/native/src/internal/TimeZoneRules.kt

@@ -167,7 +167,7 @@ internal class RecurringZoneRules(
             val ldtAfter = rule.transitionDateTime.toLocalDateTime(rule.offsetAfter)
             return if (localDateTime < ldtBefore && localDateTime < ldtAfter) {
                 OffsetInfo.Regular(rule.offsetBefore)
-            } else if (localDateTime > ldtBefore && localDateTime >= ldtAfter) {
+            } else if (localDateTime >= ldtBefore && localDateTime >= ldtAfter) {
                 offset = rule.offsetAfter
                 continue
             } else if (ldtAfter < ldtBefore) {

core/tzfile/test/TimeZoneRulesTest.kt

@@ -22,10 +22,13 @@ class TimeZoneRulesTest {
         // on the last Sunday in October.
         val dstStartTime = LocalDateTime(2040, 3, 25, 2, 0)
         val infoAtDstStart = rules.infoAtDatetime(dstStartTime)
-        assertTrue(infoAtDstStart is OffsetInfo.Gap, "Expected Gap, got $infoAtDstStart")
+        assertIs<OffsetInfo.Gap>(infoAtDstStart)
         val dstEndTime = LocalDateTime(2040, 10, 28, 3, 0)
         val infoAtDstEnd = rules.infoAtDatetime(dstEndTime)
-        assertTrue(infoAtDstEnd is OffsetInfo.Overlap, "Expected Overlap, got $infoAtDstEnd")
+        assertIs<OffsetInfo.Regular>(infoAtDstEnd)
+        val timeBeforeDstEnd = LocalDateTime(2040, 10, 28, 2, 59, 59, 999_999_999)
+        val infoBeforeDstEnd = rules.infoAtDatetime(timeBeforeDstEnd)
+        assertIs<OffsetInfo.Overlap>(infoBeforeDstEnd)
     }
 
     @Test