Never compile your widgetset again with Gradle build-cache

Widgetset compile is one of the most time-consuming things in any Vaadin build. On a fast machine it will usually take from just under one minute up to several minutes every time we launch a build . If we are using a smart build system like Gradle, along with a smart plugin that can monitor the inputs of the compilation we can get away with only compiling when something changes, but still in reality we will have to re-compile it from time to time. While long build times usually are not a problem when building on a CI server like Jenkins, »