Student class with encapsulation

Student.java defines Student class have following private fields:

• Name
• Grade
• Group
• secretNickName with following methods:
• getters for Grade, Name and Group
• setter for Grade
• upgrade() to move up one grade
• downgrade() to move down one grade

Student class can be used by School in the same package ('src' is used as the package in the Repo), for School/teacher to:

• initialize a student record. Note the Constructor
• input a Grade for the student
• upgrade or downgrade to a student's grade

Main.java can be run to test the Student Class methods.