Thank you for this addon… jfyi, you left the rebel.xml in the jar ;)
Invalid rebel.xml: Invalid ‘dir’ defined in class path of rebel.xml (jar:file:/Applications/IS/webapps/flow/WEB-INF/lib/lazy-download-button-1.0.0.jar!/rebel.xml): Directory ‘C:/Arbeit/workspace/vaadin_directory/lazydownloadbutton/target/classes’ does not exist