Preserve fixed-offset ORC timezone rules

Signed-off-by: Chong Gao <chongg@nvidia.com>

Author: Chong Gao

src/main/java/com/nvidia/spark/rapids/jni/GpuTimeZoneDB.java

@@ -602,8 +602,8 @@ private OrcTimezoneContext(Table writerTzInfoTable, Table readerTzInfoTable,
           readerTzInfo.transitions == null || readerTzInfo.transitions.length == 0
               ? Long.MIN_VALUE
               : TimeUnit.MILLISECONDS.toMicros(readerTzInfo.transitions[0]);
-      TimeZone writerTz = TimeZone.getTimeZone(getZoneId(writerTimezone).getId());
-      TimeZone readerTz = TimeZone.getTimeZone(getZoneId(readerTimezone).getId());
+      TimeZone writerTz = TimeZone.getTimeZone(getZoneId(writerTimezone));
+      TimeZone readerTz = TimeZone.getTimeZone(getZoneId(readerTimezone));
       this.writerReaderRulesDiffer = !writerTz.hasSameRules(readerTz);
     }
 

src/test/java/com/nvidia/spark/rapids/jni/GpuTimeZoneDBTest.java

@@ -43,7 +43,7 @@ public class GpuTimeZoneDBTest {
   private static final long MICROS_PER_SECOND = TimeUnit.SECONDS.toMicros(1);
 
   private static TimeZone getTimeZoneForOrc(String timezoneId) {
-    return TimeZone.getTimeZone(GpuTimeZoneDB.getZoneId(timezoneId).getId());
+    return TimeZone.getTimeZone(GpuTimeZoneDB.getZoneId(timezoneId));
   }
 
   private static long orc2015YearBaseOffsetUs(String timezoneId) {
@@ -190,6 +190,30 @@ void testConvertOrcTimezonesCorrectsIgnoredWriterTimezoneEpochBorrow() {
     }
   }
 
+  @Test
+  void testConvertOrcTimezonesFixedOffsetIds() {
+    GpuTimeZoneDB.cacheDatabase();
+    GpuTimeZoneDB.verifyDatabaseCached();
+
+    long[] microseconds = {0L, -1L, 1L, -2_957_649_381_472_612L};
+    String[][] cases = {
+        {"UTC", "+05:30"},
+        {"+05:30", "UTC"},
+        {"UTC", "EST"},
+        {"EST", "UTC"}
+    };
+
+    for (String[] timezones : cases) {
+      try (ColumnVector input = ColumnVector.timestampMicroSecondsFromLongs(microseconds);
+          ColumnVector expected =
+              convertOrcTimezonesOnCPU(microseconds, timezones[0], timezones[1]);
+          ColumnVector actual =
+              GpuTimeZoneDB.convertOrcTimezones(input, timezones[0], timezones[1])) {
+        assertColumnsAreEqual(expected, actual);
+      }
+    }
+  }
+
   @Test
   void testConvertOrcTimezones() {
     GpuTimeZoneDB.cacheDatabase();