Suppose we have a custom class org.me.Person.java in the src directory of a web application. When we change something in the source code of the class and then click Save we hope to see changes in the corresponding class in the build/web/WEB-INF/classes directory. It's true for ant-based web projects. But for Maven based the behavior depends on the IncrementalDeployment (or IncrementalDeployment2) implementation of the method getDirectoryForModule(TargetModuleID). When the method returns null then NetBeans API changes the Person.class in the target/<project-name>/WEB-INF/classes directory. To avoid jar and/or locking on the Windows a server can copy the original build/web or target/<project-name> to a temporary directory when the web application initially deployed. If the method getDirectoryForModule returns that copy instead of the original one, then NetBeans doesn't change target/<project-name>/WEB-INF/classes for maven-based projects and works nice for ant-based projects. All changes of the classes are in the target/classes directory.