SpringJPA - inconsistent datatypes: expected NUMBER got BINARY

Im using SPRING JPA in my application and trying to run a native query as follows:

@Query (value="select max(ts) from abc.test s         \n" + 
                        "where abc.getTest(s.user_id)  = :#{#userId}            \n" + 
                        "and upper(app_name) = 'TAX' and INSTR(s.user_id, '.') > 0        \n" + 
                        "group by user_id, app_name", nativeQuery=true)
Timestamp getLastLogin(BigDecimal userId);

I am getting exception as follows:

Caused by: Error : 932, Position : 110, Sql = select max(ts) from abc.test s         
where ac.getTest(s.user_id)  = :1             
and upper(app_name) = 'TAX' and INSTR(s.user_id, '.') > 0        
group by user_id, app_name, OriginalSql = select max(ts) from abc.test s         
where abc.getTest(s.user_id)  = ?            
and upper(app_name) = 'TAX' and INSTR(s.user_id, '.') > 0        
group by user_id, app_name, Error Msg = ORA-00932: inconsistent datatypes: expected NUMBER got BINARY

    at oracle.jdbc.driver.T4CTTIoer11.processError(T4CTTIoer11.java:514)
    ... 109 more
<org.hibernate.engine.jdbc.spi.SqlExceptionHelper> <SqlExceptionHelper> <logExceptions> <SQL Error: 932, SQLState: 42000> 
<org.hibernate.engine.jdbc.spi.SqlExceptionHelper> <SqlExceptionHelper> <logExceptions> <ORA-00932: inconsistent datatypes: expected NUMBER got BINARY
> 

I tried to convert the max(ts) to string using to_char and changed the coresponding getter/setter to String still getting the same issue.

Update: I fixed it with this small change

String getLastLogin(@Param("userId") BigDecimal userId); Didnt add @Param for the arguments.