I just downloaded Pet Clinic example (I would like to rewrite it to Spring Portlet MVC) and in every package there is package-info.java class. File is empty except the package declaration, so what purpose does this serve?And can I safely omit this in Spring Portlet MVC?
You can safely delete these but normally from my experience you'd just put a description of what the package is for in a comment in this file.
You can find more info on the Oracle website here