yWorks UML Doclet fails to generate UML diagrams

First, you need to specify one of yWorks UML Doclet's UML generation options:

• -umlgen (generates UML diagrams if the source documentation contains an explicit @y.uml Javadoc tag)
• -umltypegen (generates UML diagrams for all documented classes and interfaces)
• -umlpackagegen (generates UML diagrams for all documented packages)
• -umloverviewgen (generates project overview UML diagrams)
• -umlautogen (generates all types of UML diagrams)

Second, you need to specify the path to your compiled, unobfuscated Java class files (and all libraries your Java files depend on) in the -docletpath option.
Your .class files (and the libraries) may be located in a .jar file.