A DESCRIPTION OF THE PROBLEM :
     // Compute sum of salaries of employee
     int total = employees.stream()
                          .collect(Collectors.summingInt(Employee::getSalary)));

should be:

     // Compute sum of salaries of employee
     int total = employees.stream()
                          .collect(Collectors.summingInt(Employee::getSalary));



EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
     // Compute sum of salaries of employee
     int total = employees.stream()
                          .collect(Collectors.summingInt(Employee::getSalary));

i.e. remove the last ')'
ACTUAL -
     // Compute sum of salaries of employee
     int total = employees.stream()
                          .collect(Collectors.summingInt(Employee::getSalary)));

i.e. one ')' too many



URL OF FAULTY DOCUMENTATION :
https://docs.oracle.com/javase/8/docs/api/java/util/stream/Collectors.html