I'm very embarrassed, but I'm using the spring tool suite for Java development
The image below is in the state, but I'm having trouble understanding the procedure for displaying the development folder hierarchy on the left side of the screen. .. ..

It doesn't come out whether the method of investigation is bad or too rudimentary. .. ..
I created the folder itself once and displayed it up to "Hello World", so it can't be missing. .. ..

Help me. .. ..