There is a bug in the PrimeFaces 6.1 pdf doc on page 28:
One would expect a number in column number 2.minQueryLength | true | Integer | Number of characters to be typed before starting to query.
Also, the autoComplete component does not work as I expect on FireFox 57, Tomcat 8, Mojarra 2.3.2 and PrimeFaces 6.1.11. Since minQueryLength specifies the number of characters the user must type, I would expect a value of 0 (zero) to trigger a query and render a panel with options when the autoComplete gets focus.
In other words: if minQueryLength="0" and the user clicks in or tabs to an autoComplete, I would expect the suggestions for an empty query to appear.
Cheers,
Leo Mekenkamp