Car Detailing Inc maintains a file of past customers: a customer number, name, address, date of job, and price of job. It also keeps a file of estimates given for work not yet performed; the file contains columns for a customer number, name, address, proposed date of job, and proposed price. Each file is in customer number order. Design code in Java that merges the two files to create one combined text file of all customers whether past or pending with no duplicates; even for when a customer who has been given an estimate is also a past customer, go ahead and use the proposed data.