Calling a sql function from java gives error

Question

I'm calling a SQL function which takes a string parameter (varchar2 in SQL) and returns a SYS_REFCURSOR which I'm trying to get in Java using below code.

My function is

CREATE OR REPLACE FUNCTION check_query(p_query_text VARCHAR2) RETURN SYS_REFCURSOR IS
    txt VARCHAR2(4000);
    from_clause VARCHAR2(4000);
    l_qry NVARCHAR2(4000);
    ret SYS_REFCURSOR; -- Define the SYS_REFCURSOR type for result set
    total_count NUMBER; -- Variable to store the total count

BEGIN
    IF p_query_text IS NOT NULL THEN
        txt := p_query_text;
        from_clause := 'toa_app_data WHERE';

        IF txt IS NOT NULL AND LENGTH(txt) > 0 THEN
            l_qry := 'SELECT * FROM toa_app_data WHERE app_id IN (SELECT toa_app_data.app_id FROM ' || from_clause ||
                     ' ' || txt || ') FETCH FIRST 5 ROWS ONLY'; -- Fetch top 5 rows
        ELSE
            l_qry := 'SELECT * FROM toa_app_data WHERE 1 = 0'; -- Return empty result set
        END IF;
            DBMS_OUTPUT.PUT_LINE('l_qry: ' || l_qry);
        OPEN ret FOR l_qry; -- Open the cursor for the top 5 rows or empty result set

        -- Get the total count for the query
        EXECUTE IMMEDIATE 'SELECT COUNT(*) FROM toa_app_data WHERE app_id IN (SELECT toa_app_data.app_id FROM ' || from_clause || ' ' || txt || ')'
        INTO total_count;

    ELSE
        -- Open an empty cursor when p_query_text is NULL
        OPEN ret FOR SELECT * FROM toa_app_data WHERE 1 = 0;

        -- Set total_count as 0 when there is no input query
        total_count := 0;
    END IF;

    -- Print the total count (optional)
    DBMS_OUTPUT.PUT_LINE('Total count: ' || total_count);

    RETURN ret; -- Return the SYS_REFCURSOR with the top 5 rows or an empty cursor
END check_query;

In Java I'm trying to get the result of this using below function

public List validateQuery(String queryString) throws SQLException{
    logger.debug("In validateQuery: query- ");
    //String retValue = null;
    Long totalCount = 0L;
    List list = new ArrayList();
    try{
        StoredProcedureQuery query = queryDao.getEntityManager().createStoredProcedureQuery(VALIDATE_QUERY_BEFORE_SAVE);
        query.registerStoredProcedureParameter(QUERY_STRING_TEXT, String.class, ParameterMode.IN);
        query.setParameter(QUERY_STRING_TEXT, queryString);
        query.registerStoredProcedureParameter("ret", Class.forName("java.sql.ResultSet"), ParameterMode.REF_CURSOR);
        query.registerStoredProcedureParameter("total_count", Long.class, ParameterMode.OUT);
        query.execute();
        list = query.getResultList();
        //retValue = (String) query.getOutputParameterValue("ret");
        totalCount = ((Number) query.getOutputParameterValue("total_count")).longValue();
    
        
    }catch (Exception ex) {
            logger.error(ex.getMessage(), ex);
        }
    
    return list;
}

In the logs I get the error as

Caused by: java.sql.SQLException: ORA-06550: line 1, column 7: PLS-00306: wrong number or types of arguments in call to 'CHECK_QUERY' ORA-06550: line 1, column 7: PL/SQL: Statement ignored

Not sure how. Also Class.forName("java.sql.ResultSet") this seems to be correct as I was just testing it and could not find a class myself but this code gives a ResultSet class. the error comes when we do query.execute().

It's a simple SQL validator and we pass the where clause and to confirm if the query is correct or not, if correct then return the total count and top 5 rows from the query if not then return the SQL error