How to write "in" claus in select query when ever in_put param has some values..?

whenever users pass a list of values then we need to pause "in" condition.
the jin_son_doc will be like this "India,American Samoa"

create or replace PROCEDURE test_attendee (
    out_chr_err_code   OUT                VARCHAR2,
    out_chr_err_msg    OUT                VARCHAR2,
    out_attendee_tab   OUT                return_attendee_arr_result,
    in_json_doc        IN                 VARCHAR2
) IS

    l_chr_srcstage        VARCHAR2(200);
    l_chr_biqtab          VARCHAR2(200);
    l_chr_srctab          VARCHAR2(200);
    l_chr_bistagtab       VARCHAR2(200);
    l_chr_err_code        VARCHAR2(255);
    l_chr_err_msg         VARCHAR2(255);
    l_out_chr_errbuf      VARCHAR2(2000);
    lrec                  return_attendee_report;
    l_num_counter         NUMBER := 0;
    json_doc              CHAR_ARRAY(1000) := in_json_doc;
    CURSOR cur_attendee_data IS
    SELECT
        *
    FROM
        (
            SELECT
                a.*,
                ROWNUM rn
            FROM
                (SELECT * FROM (
                    SELECT
                        r.id              request_id,
                        c.designation     ext_att_title,
                        DECODE(c.attendee_type, 'externalattendees', 'External', 'Internal') attendee_type
                    FROM
                        bi_request r
                        LEFT JOIN bi_request_activity_day a ON a.request_id = r.id
                        LEFT JOIN bi_request_catering_activity b ON b.request_activity_day_id = a.id
                        LEFT JOIN bi_request_attendees c ON c.request_id = r.id
                        LEFT JOIN bi_request_act_day_room d ON d.request_activity_day_id = a.id
                                                               AND d.room = b.room
                    WHERE
                        r.state = 'CONFIRMED'
                        AND a.event_date BETWEEN l_start_date AND l_end_date
                        AND r.location_id = (
                            SELECT UNIQUE
                                ( id )
                            FROM
                                bi_location
                            WHERE
                                unique_id = l_location_id
                        )
                        AND d.room_type = 'MAIN_ROOM'
                        AND country IN (
                            SELECT
                                column_value
                            FROM
                                TABLE ( json_doc )
                        )
                    
                )
                WHERE
                1=1

                ) a
            WHERE
                ROWNUM <= l_end_row
        )
    WHERE
        rn >= l_start_row;

    TYPE rec_attendee_data IS
        TABLE OF cur_attendee_data%rowtype INDEX BY PLS_INTEGER;
    l_cur_attendee_data   rec_attendee_data;
BEGIN
        dbms_output.put_line(l_country_array.count);

    out_attendee_tab := return_attendee_arr_result();
    OPEN cur_attendee_data;
    LOOP
        FETCH cur_attendee_data BULK COLLECT INTO l_cur_attendee_data;
        EXIT WHEN l_cur_attendee_data.count = 0;
        dbms_output.put_line('here in first insert');

        lrec := return_attendee_report();
        out_attendee_tab := return_attendee_arr_result(return_attendee_report());
        out_attendee_tab.DELETE;
        FOR i IN 1..l_cur_attendee_data.count LOOP


--						 dbms_output.put_line('Inside cursor   '  );
            BEGIN
                l_num_counter := l_num_counter + 1;
                lrec := return_attendee_report();
                lrec.requestid := l_cur_attendee_data(i).request_id;
                 lrec.attendeetype := l_cur_attendee_data(i).attendee_type;
                lrec.attendeetype := json_doc;
                IF l_num_counter > 1 THEN
                    out_attendee_tab.extend();
                    out_attendee_tab(l_num_counter) := return_attendee_report();
                ELSE
                    out_attendee_tab := return_attendee_arr_result(return_attendee_report());
                END IF;

                out_attendee_tab(l_num_counter) := lrec;
            EXCEPTION
                WHEN OTHERS THEN
                    dbms_output.put_line('Error occurred : ' || sqlerrm);
            END;
        END LOOP;

    END LOOP;

EXCEPTION
    WHEN OTHERS THEN
        dbms_output.put_line('HERE INSIIDE OTHERS' || sqlerrm);
END;

Whenever j"son_doc" is null we need to skip the in clause. Is this possible, let me know if we have any solution.

user will pass jin_son_doc will be like this "India, America".

by using the following function i'm converting string to array,

create or replace FUNCTION fn_varchar_to_array(p_list IN VARCHAR2)
      RETURN CHAR_ARRAY
    AS
      l_string       VARCHAR2(32767) := p_list || ',';
      l_comma_index  PLS_INTEGER;
      l_index        PLS_INTEGER := 1;
      l_tab          CHAR_ARRAY := CHAR_ARRAY();
    BEGIN
      LOOP
       l_comma_index := INSTR(l_string, ',', l_index);
       EXIT WHEN l_comma_index = 0;
       l_tab.EXTEND;
       l_tab(l_tab.COUNT) := SUBSTR(l_string, l_index, l_comma_index - l_index);
       l_index := l_comma_index + 1;
     END LOOP;
     RETURN l_tab;
   END fn_varchar_to_array;

You can use OR condition as following:

....
AND (json_doc is null
  OR country IN (
                 SELECT
                    column_value
                  FROM
                     TABLE ( json_doc )
                 )
)
...

Cheers!!