use columnIndexToName in getTimestamp

Author: mzitnik

jdbc-v2/src/main/java/com/clickhouse/jdbc/ResultSetImpl.java

@@ -1092,23 +1092,7 @@ public Time getTime(String columnLabel, Calendar cal) throws SQLException {
 
     @Override
     public Timestamp getTimestamp(int columnIndex, Calendar cal) throws SQLException {
-        checkClosed();
-        try {
-            LocalDateTime localDateTime = reader.getLocalDateTime(columnIndex);
-            if (localDateTime == null) {
-                wasNull = true;
-                return null;
-            }
-            Calendar c = (Calendar) (cal != null ? cal : defaultCalendar).clone();
-            c.set(localDateTime.getYear(), localDateTime.getMonthValue() - 1, localDateTime.getDayOfMonth(), localDateTime.getHour(), localDateTime.getMinute(),
-                    localDateTime.getSecond());
-            Timestamp timestamp = new Timestamp(c.getTimeInMillis());
-            timestamp.setNanos(localDateTime.getNano());
-            wasNull = false;
-            return timestamp;
-        } catch (Exception e) {
-            throw ExceptionUtils.toSqlState(String.format("SQL: [%s]; Method: getTimestamp(%s)", parentStatement.getLastSql(), columnIndex), e);
-        }
+        return getTimestamp(columnIndexToName(columnIndex), cal);
     }
 
     @Override