Cannot see "file,line,func" fields in the journal

I am trying to use sd_journal_print_with_location() function.

#include 

int main() {
    sd_journal_print_with_location(LOG_INFO, "CODE_FILE=tst_file.c", "CODE_LINE=123", "main", "message");
    return 0;
}

And then execute:

$ gcc -o tst_file tst_file.c -lsystemd
$ ./tst_file
$ journalctl --identifier=tst_file
Dec 11 12:29:17 MYBOX tst_file: message

So the question is: Where are file, line, and func fields? Why cannot I see them with the journalctl? What am I doing wrong?