Write a Java program: Subscription Cost calculator.

READ BEFORE ANSWERING:

The Code should be complete without any errors and should execute.

Incomple code or code with erros and logical problem will get a downvote.

Consider the following:

1] Use the Design principles and design patterns in the code

2] Write Executable code with Junit Tests and Console Tests.

Given the pricing plan (monthly) for products and customers would subscribe to the list of products.

JSON Structure :

[{

"planId": "BASIC",

"monthlyCost": "9.99"

}, {

"planId": "STANDARD",

"monthlyCost": "49.99"

}, {

"planId": "PREMIUM",

"monthlyCost": "249.99"

}]

// Customer subscription information

{

"customerId": "c1",

"product": {

"name": "Jira",

"subscription" : {

"planId": "BASIC",

"startDate": "2021-01-01" // YYYY-MM-DD format

}

}

}

Create model classes and service class (s) (CostExplorer) to expose the below two APIs:

monthlyCostList(): Array/List of size 12 filled with the cost incurred in each month of the unit year

annualCost(): Total cost in a unit year

Consider the annual package from JAN - DEC.

For simplicity, let's assume we will charge the customer for the entire month even if the customer is subscribing any day after the 1st of the month.