Java 11 iterar hashmap

//Error en la línea 24
import java.util.Arrays;
import java.util.HashMap;
import java.util.Scanner;

public class Question4Day2 {
    public static void main(String[] args) {
        HashMap studentsGrades = new HashMap<String, Double>();
        Scanner inputScanner = new Scanner(System.in);
        Double classAverage = 0.0;
        //Double studentNumber = 0.0;
        while (true) {
            String name;
            Double grade;
            System.out.println("Student name:");
            name = inputScanner.next();
            System.out.println(name + "'s Grade");
            grade = Double.parseDouble(inputScanner.next());
            if (grade == -1) {
                //classAverage = classAverage/studentNumber;
                break;
            } else {
                //**!LÍNEAS QUE DAN ERROR¡**
                for (HashMap.Entry<Double, Integer> studentGrade :
                        studentsGrades.entrySet()
                ) {
                    System.out.println("prueba");
                }
                /*Incompatible types.
                Required:Object
                Found: Entry<java.lang.String,java.lang.Double>*/
                //classAverage += grade;
                //studentNumber++;
                studentsGrades.put(name, grade);
            }
        }
        System.out.println(Arrays.asList(studentsGrades));
        System.out.println("Average of the class: " + classAverage);
    }
}