Changing a JSON object parsed with APEX_JSON - plsql

Question

I would like to be able to change a JSON object parsed with the APEX_JSON.parse() function, but I found nothing in the official documentation, no tips or examples about that.
In the code below I putted comments in the specific points in order to give a clear idea about my need.
SET SERVEROUTPUT ON
DECLARE
j apex_json.t_values;
l_paths apex_t_varchar2;
writers clob;
json_object_result clob;
BEGIN
writers := '[
{
"id": null,
"hashCode": "7ef605fc8dba5425d6965fbd4c8fbe1f",
"description": "Machado de Assis",
"base64Img": "8eNZ28Dh5rZQIPhNEfwqoo1LCVx..."
},
{
"id": 151,
"hashCode": "a8f15eda80c50adb0e71943adc8015cf",
"description": "José Alencar",
"base64Img": "/XIQIHCol8eNZ28Dh5rZQIPhNEfwqoo1LCVx/9k=..."
}
]';
apex_json.parse(j, writers);
l_paths := apex_json.find_paths_like (
p_values => j,
p_return_path => '[%]',
p_subpath => '.hashCode',
p_value => '7ef605fc8dba5425d6965fbd4c8fbe1f'
);
dbms_output.put_line('Itens found: ' || l_paths.count);
if (l_paths.count = 1) then
dbms_output.put_line('id: ' || apex_json.get_varchar2(p_values => j, p_path => l_paths(1) || '.id'));
dbms_output.put_line('hashCode: ' || apex_json.get_varchar2(p_values => j, p_path => l_paths(1) || '.hashCode'));
dbms_output.put_line('description: ' || apex_json.get_varchar2(p_values => j, p_path => l_paths(1) || '.description'));
dbms_output.put_line('base64Img: ' || apex_json.get_varchar2(p_values => j, p_path => l_paths(1) || '.base64Img'));
-- Here I would like to nullify base64Img attribute value
json_object_result := 'here goes the object matched in the search with the base64Img attribute value null';
end if;
END;
In my json_object_result variable I would like to save the JSON object matched in the apex_json.find_paths_like() with its base64Img attribute null. In my example the result would be
{
"id": null,
"hashCode": "7ef605fc8dba5425d6965fbd4c8fbe1f",
"description": "Machado de Assis",
"base64Img": ""
}
or
{
"id": null,
"hashCode": "7ef605fc8dba5425d6965fbd4c8fbe1f",
"description": "Machado de Assis"
}
Is it possible to make something like that with APEX_JSON?