For this milestone, you will focus on delivering the contact services. The purpose of these services is to add, update, and delete contact objects within the application.

The contact service uses in$-$memory data structures to support storing contacts $($no database required$).$ In addition, there is no user interface for this milestone. You will verify the contact service through JUnit tests. The contact service contains a contact object along with the contact service. The requirements are outlined below.

Contact Class Requirements

The contact object shall have a required unique contact ID string that cannot be longer than $10$ characters. The contact ID shall not be null and shall not be updatable.

The contact object shall have a required firstName String field that cannot be longer than $10$ characters. The firstName field shall not be null.

The contact object shall have a required lastName String field that cannot be longer than $10$ characters. The lastName field shall not be null.

The contact object shall have a required phone String field that must be exactly $10$ digits. The phone field shall not be null.

The contact object shall have a required address field that must be no longer than $30$ characters. The address field shall not be null.

Contact Service Requirements

The contact service shall be able to add contacts with a unique ID$.$

The contact service shall be able to delete contacts per contact ID$.$

The contact service shall be able to update contact fields per contact ID$.$ The following fields are updatable:

firstName

lastName

Number

Address

To complete this project, you must submit a Contact Service zipped folder containing the following deliverables:

Contact.java

ContactService.java

ContactTest.java

ContactServiceTest.java

import java.util.HashMap;

public class ContactService $\{$

private final HashMap contacts $=$ new HashMap$<>()$;

public void addContact$($Contact contact$)\{$

if $($contacts$.$containsKey$($contact$.$getFirstName$()))\{$

throw new IllegalArgumentException$("$Contact with this ID already exists"$)$;

$\}$

contacts.put$($contact$.$getFirstName$(),$ contact$)$;

$\}$

public void deleteContact$($String contactID$)\{$

contacts.remove$($contactID$)$;

$\}$

public void updateContact$($String contactID, String newFirstName, String newLastName, String newPhone, String newAddress$)\{$

Contact contact $=$ contacts.get$($contactID$)$;

if $($contact $==$ null$)\{$

throw new IllegalArgumentException$("$Contact not found"$)$;

$\}$

contact.setFirstName$($newFirstName$)$;

contact.setLastName$($newLastName$)$;

contact.setPhone$($newPhone$)$;

contact.setAddress$($newAddress$)$;

$\}$

public Contact getContact$($String contactID$)\{$

return contacts.get$($contactID$)$;

$\}$

$\}$

public class Contact $\{$

private final String contactID; $//$ not updatable

private String firstName;

private String lastName;

private String phone;

private String address;

public Contact$($String contactID, String firstName, String lastName, String phone, String address$)\{$

if $($contactID $==$ null $||$ firstName $==$ null $||$ lastName $==$ null $||$ phone $==$ null $||$ address $==$ null$)\{$

throw new IllegalArgumentException$("$Fields cannot be null"$)$;

$\}$

if $($contactID$.$length$()>10||$ firstName.length$()>10||$ lastName.length$()>10||$ phone.length$()!=10||$ address.length$()>30)\{$

throw new IllegalArgumentException$("$Invalid field lengths"$)$;

$\}$

this.contactID $=$ contactID;

this.firstName $=$ firstName;

this.lastName $=$ lastName;

this.phone $=$ phone;

this.address $=$ address;

$\}$

$//$ Getters and Setters for updatable fields

$//$ Omitted getter for contactID since it's not updatable

public String getFirstName$()\{$

return firstName;

$\}$

public void setFirstName$($String firstName$)\{$

if $($firstName $==$ null $||$ firstName.length$()>10)\{$

throw new IllegalArgumentException$("$Invalid first name"$)$;

$\}$

this.firstName $=$ firstName;

$\}$

public String getLastName$()\{$

return lastName;

$\}$

public void setLastName$($String lastName$)\{$

if $($lastName $==$ null $||$ lastName.length$()>10)\{$

throw new IllegalArgumentException$("$Invalid last name"$)$;

$\}$

this.lastName $=$ lastName;

$\}$

public String getPhone$()\{$

return phone;

$\}$

public void setPhone$($String phone$)\{$

if $($phone $==$ null $||$ phone.length$()!=10)\{$

throw new IllegalArgumentException$("$Invalid phone"$)$;

$\}$

this.phone $=$ phone;

$\}$

public String getAddress$()\{$

return address;

$\}$

public void setAddress$($String address$)\{$

if $($address $==$ null $||$ address.length$()>30)\{$

throw new IllegalArgumentException$("$Invalid address"$)$;

$\}$

this.address $=$ address;

$\}$

$\}$

Please help with test classes.