How do i get the content of the BufferStrategy/its Graphics in Java?

Question

is there a way to get the content of the current Buffer im writing to? a sort of a representation of what i've written to its graphics. For example, in the following code, i would like to get a BufferedImage or even an Array that has values that represent what i've written, in this case; a black background and a white rectangle:

public static void render (Canvas canvas) {
        BufferStrategy buffer = canvas.getBufferStrategy();
        Graphics g = buffer.getDrawGraphics();
        
        g.setColor(Color.BLACK);
        g.fillRect(0, 0, canvas.getWidth(), canvas.getHeight());

        g.setColor(Color.WHITE);
        g.drawRect(50, 50, 100, 100);   

        g.dispose();
        // Maybe a method here that allows me to get what has been writen?
        buffer.show();                  
    }

Thanks in advance!