Designing modules

Over the years, the first step in designing a Java application has usually involved the design of the packages and classes, as well as the interactions between them. It also perhaps involved designing some shared libraries. For instance, you'd move reusable code into a separate project and bundle it into your application as a JAR file. With Java 9 modules, you now have a new aspect to consider that significantly impacts the design process. Irrespective of whether you are creating a new application from scratch or you are migrating an existing classpath application into a modular application, there are some common questions you'll need to answer--How do you come up with a modular design? How do you choose what a module should be? How much code and functionality should be in a module? Where do you draw module boundaries in specific scenarios? For example...