I have WordPress 4.6.1. I now have experience with creating custom post types and see them stacked up in the admin UI console. But how can I create a stack all of my custom post types in a menu so that when I go to wp-admin, I see on the left, a button called My Post Types, and if I hover over it, it shows me all of my custom post types displayed in a list format.
I'm going to assuming when you say that you "hover over it, it shows custom post types displayed in a list" you mean submenus. The below uses
admin_menu to create a blank Parent Menu then we loop through the public post types to display them as submenus:
add_menu_page() needs to be passed some sort of link - since we would have nothing to show at that link ( there's no
post_type tied to this page, it's a dummy page ) I've opted to link to
get_post_types() function has a few parameters to filter on if
public doesn't work for your case.