import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
 
public class Main {
    public static void main(String[] args) {
        DateTimeFormatter dtfInput = DateTimeFormatter.ofPattern("u-M-d'T'H:m:s.SSSSSSS", Locale.ENGLISH);
        DateTimeFormatter dtfOutput = DateTimeFormatter.ofPattern("uuuu-MM-dd HH:mm:ss.SSSSSSS", Locale.ENGLISH);
        String strDateTime = "2021-05-31T14:12:44.8020000";
        LocalDateTime ldt = LocalDateTime.parse(strDateTime, dtfInput);
        System.out.println(ldt.format(dtfOutput));
    }
}

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