[iceberg] Fix ClassCastException reading timestamp with local timezone columns

paimon-core/src/main/java/org/apache/paimon/iceberg/manifest/IcebergConversions.java

@@ -126,6 +126,14 @@ private static ByteBuffer timestampToByteBuffer(Timestamp timestamp, int precisi
                 .putLong(0, timestamp.toMicros());
     }
 
+    private static Timestamp timestampFromBytes(byte[] bytes, int precision) {
+        Preconditions.checkArgument(
+                precision >= 3 && precision <= 6,
+                "Paimon Iceberg compatibility only support timestamp type with precision from 3 to 6.");
+        long encoded = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN).getLong();
+        return precision == 3 ? Timestamp.fromEpochMillis(encoded) : Timestamp.fromMicros(encoded);
+    }
+
     private static ByteBuffer timeToByteBuffer(int millisOfDay, int precision) {
         Preconditions.checkArgument(
                 precision >= 0 && precision <= 3,
@@ -164,17 +172,11 @@ public static Object toPaimonObject(DataType type, byte[] bytes) {
                 return Decimal.fromUnscaledBytes(
                         bytes, decimalType.getPrecision(), decimalType.getScale());
             case TIMESTAMP_WITHOUT_TIME_ZONE:
+                return timestampFromBytes(bytes, ((TimestampType) type).getPrecision());
             case TIMESTAMP_WITH_LOCAL_TIME_ZONE:
-                int timestampPrecision = ((TimestampType) type).getPrecision();
-                long timestampLong =
-                        ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN).getLong();
-                Preconditions.checkArgument(
-                        timestampPrecision >= 3 && timestampPrecision <= 6,
-                        "Paimon Iceberg compatibility only support timestamp type with precision from 3 to 6.");
-                if (timestampPrecision == 3) {
-                    return Timestamp.fromEpochMillis(timestampLong);
-                }
-                return Timestamp.fromMicros(timestampLong);
+                // LocalZonedTimestampType does not extend TimestampType, so it cannot
+                // share a switch arm with TIMESTAMP_WITHOUT_TIME_ZONE.
+                return timestampFromBytes(bytes, ((LocalZonedTimestampType) type).getPrecision());
             case TIME_WITHOUT_TIME_ZONE:
                 int timePrecision = ((TimeType) type).getPrecision();
                 Preconditions.checkArgument(

paimon-core/src/test/java/org/apache/paimon/iceberg/manifest/IcebergConversionsTimestampTest.java

@@ -125,4 +125,20 @@ void testToPaimonObjectTimestampInvalid(int precision, long serializedMicros) {
     private static Stream<Arguments> provideInvalidTimestampCases() {
         return Stream.of(Arguments.of(0, 1698686153L), Arguments.of(9, 1698686153123456789L));
     }
+
+    @ParameterizedTest
+    @MethodSource("provideTimestampToPaimonCases")
+    @DisplayName("toPaimonObject decodes TIMESTAMP_WITH_LOCAL_TIME_ZONE without ClassCastException")
+    void testToPaimonObjectForTimestampWithLocalTimeZone(
+            int precision, long serializedMicros, String expectedTs) {
+        byte[] bytes = new byte[8];
+        ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN).putLong(serializedMicros);
+
+        Timestamp actual =
+                (Timestamp)
+                        IcebergConversions.toPaimonObject(
+                                DataTypes.TIMESTAMP_WITH_LOCAL_TIME_ZONE(precision), bytes);
+
+        assertThat(actual.toString()).isEqualTo(expectedTs);
+    }
 }