Given an array of primitive integers named grades, fill in the blank to complete the following code that calculates the average of all the grades: double average = 0; average + grades[ average (= grades.length; Use proper spacing per the course style guide. Do not include additional spaces at the beginning or end. Given an array of primitive integers named grades, fill in the blank to complete the following code that calculates the average of all the grades: double average = 0; average + grades[ average (= grades.length; Use proper spacing per the course style guide. Do not include additional spaces at the beginning or end