/*

You have two classes: Employee (name: String, salary: Long) and Department

(name: String, code: String, employees: List<Employee>).

Both classes have getters for all fields with the corresponding names (getName(), getSalary(), getEmployees() and so on).

Write a method using Stream API that calculates the general number of employees with salary >= threshold for all departments

whose code starts with string "111-" (without ""). Perhaps, flatMap method can help you to implement it.

Classes Employee and Department will be available during testing. You can define your own classes for local testing.

Important. Use the given template for your method. Pay attention to type of an argument and the returned value.

Please, use only Stream API, no cycles.

Examples: there are 2 departments (in JSON notation) below and threshold = 20 000.

The result is 1 (because there is only one suitable employee).

[

{

"name": "dep-1",

"code": "111-1",

"employees": [

{

"name": "William",

"salary": 20000

},

{

"name": "Sophia",

"salary": 10000

}

]

},

{

"name": "dep-2",

"code": "222-1",

"employees": [

{

"name": "John",

"salary": 50000

}

]

}

]

*/

public static long calcNumberOfEmployees(List<Department> departments, long threshold) {

return departments.stream()

.filter(s -> s.code.startsWith("111-"))

.flatMap(s -> s.getEmployees().stream().filter(e -> e.getSalary() >= threshold)).count();

}