this is the full question and these are the classes code:

import java.util.List;

class Manufacturer {

private String name;

List drugs;

public Manufacturer(String name, List drugs) {

this.name = name;

this.drugs = drugs;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public List getDrugs() {

return drugs;

}

public void setDrugs(List drugs) {

this.drugs = drugs;

}

}

class Drug {

private String name;

private int price;

private Manufacturer manufacturer;

public Drug(String name, int price, Manufacturer manufacturer) {

this.name = name;

this.price = price;

this.manufacturer = manufacturer;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public int getPrice() {

return price;

}

public void setPrice(int price) {

this.price = price;

}

public Manufacturer getManufacturer() {

return manufacturer;

}

public void setManufacturer(Manufacturer manufacturer) {

this.manufacturer = manufacturer;

}

public class SalesRep{

// instance variables for the sales rep

private String name;

private double totalAmountSold;

private int salary;

// create getters and setters for attributes

public String getName() {

return this.name;

}

public void setName(String name) {

this.name = name;

}

public double getTotalAmountSold() {

return this.totalAmountSold;

}

public void setTotalAmountSold(double totalAmountSold) {

this.totalAmountSold = totalAmountSold;

}

public int getSalary() {

return this.salary;

}

public void setSalary(int salary) {

this.salary = salary;

}

}

Program Code to copy (FixedIncomeSalesRep.java)

public class FixedIncomeSalesRep extends SalesRep {

private int commission;

private int fixedIncome;

public int getCommission() {

return this.commission;

}

public void setCommission(int commission) {

this.commission = commission;

}

public int getFixedIncome() {

return this.fixedIncome;

}

public void setFixedIncome(int fixedIncome) {

this.fixedIncome = fixedIncome;

}

// member method to set salary

public int calculateSalary(){

int salary = (int)(commission*this.getTotalAmountSold()+fixedIncome);

this.setSalary(salary);

return salary;

}

}

Program Code to copy (CommissionSalesRep.java)

package java.sales;

public class CommissionSalesRep extends SalesRep {

private int commission;

public int getCommission() {

return this.commission;

}

public void setCommission(int commission) {

this.commission = commission;

}

// member method to set salary

public int calculateSalary(){

int salary = (int)(commission*this.getTotalAmountSold());

this.setSalary(salary);

return salary;

}

}

A Voucher is characterized by its number (int), a client name (a customer), and the quantity sold of each drug All reps and vouchers and bills are payable. As such, students need to implement an interface called Payable and implement it in the aforementioned classes, You are to create a solution for a Pharmaceutical company. Entities to be represented are: Drugs, Sales Representatives, Bills and Vouchers. A Drug is characterized by its name (string), its price (int) and its manufacturer (a manufacturer ==> composition). A Manufacturer is characterized by his name (string) and the list of drugs they sell (array of drugs) => composition. A Sales Representative (sometimes referred to as rep) is characterized by his/her name(string), the total amount sold (double), his/her salary (int). Sales Representatives can be of two types inheritance): Reps with a fixed income and a commission Reps with a commission only A Voucher is characterized by its number (int), a client name (a customer), and the quantity sold of each drug All reps and vouchers and bills are payable. As such, students need to implement an interface called Payable and implement it in the aforementioned classes. 1. You need then to create GUI interfaces where the user can manage all entities and then be able to generate a report showing the vouchers one after the other and how much as well as the total of each. 2. The user should be able to search for the vouchers of a certain customer. 3. Your GUI should also allow showing how much each rep has sold up till now and as such how much he/she has earned. 4. The system should tell which vouchers are still unpaid and how much their total is. 5. The system should allow the user to navigate between the different instances of the entities