which of the folowing method header cannot be used as method overload code example

Example 1: method overloading

//https://www.geeksforgeeks.org/overloading-in-java/
// Java program to demonstrate working of method
// overloading in Java. 
  
public class Sum { 
  
    // Overloaded sum(). This sum takes two int parameters 
    public int sum(int x, int y) 
    { 
        return (x + y); 
    } 
  
    // Overloaded sum(). This sum takes three int parameters 
    public int sum(int x, int y, int z) 
    { 
        return (x + y + z); 
    } 
  
    // Overloaded sum(). This sum takes two double parameters 
    public double sum(double x, double y) 
    { 
        return (x + y); 
    } 
  
    // Driver code 
    public static void main(String args[]) 
    { 
        Sum s = new Sum(); 
        System.out.println(s.sum(10, 20)); 
        System.out.println(s.sum(10, 20, 30)); 
        System.out.println(s.sum(10.5, 20.5)); 
    } 
}

Example 2: method overloading

Method overloading is providing two separate methods in a class 
with the same name but different arguments, while the method return type 
may or may not be different, which allows us to reuse the same method name.