use Java and Junit4 test

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Write a java function (with appropriate method name, return type and argument lists) and accompanying test program to check if the third string is a valid shuffle of the first two strings. This is true when the third string has the following constraints: The length of 3rd string is equal to length of string1 + length of string2. 3rd string should consist of letters only from string 1 and string 2. Sample Output: Enter the first String: abc Enter the second String: Def Enter the third String: dabecf Answer: True Instructions: Please review the requirements given below carefully and complete your work. You should compress all source files (including main to test your work) into a zip file and submit it through Canvas. The grading scheme is provided on Canvas. You are free to use any looping construct of your choice Make sure that you display appropriate messages that are intuitive and clear Use Java's random number generator method (limit it to integers only) Do NOT write the entire logic of the program inside main(). Create separate methods that perform all the work and then invoke it from main() Write Junit Tests for Exercise 1 and 4 only. Note: Use of Arrays is not allowed