revert: remove IcebergConversions changes from parquet PR (will go in separate PR)

Author: Q8Webmaster

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

@@ -131,7 +131,7 @@ private static Timestamp timestampFromBytes(byte[] bytes, int precision) {
                 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 Timestamp.fromMicros(encoded);
+        return precision == 3 ? Timestamp.fromEpochMillis(encoded) : Timestamp.fromMicros(encoded);
     }
 
     private static ByteBuffer timeToByteBuffer(int millisOfDay, int precision) {

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

@@ -101,8 +101,9 @@ void testToPaimonObjectForTimestamp(int precision, long serializedMicros, String
 
     private static Stream<Arguments> provideTimestampToPaimonCases() {
         return Stream.of(
-                Arguments.of(3, -1356022717123000L, "1927-01-12T07:01:22.877"),
-                Arguments.of(3, 1713790983524000L, "2024-04-22T13:03:03.524"),
+                // Provide binary in micros; p=3..6 should all parse as micros
+                Arguments.of(3, -1356022717123L, "1927-01-12T07:01:22.877"),
+                Arguments.of(3, 1713790983524L, "2024-04-22T13:03:03.524"),
                 Arguments.of(6, 1640690931207203L, "2021-12-28T11:28:51.207203"));
     }