Use provided build.gradle as script plugin

[Alexander-Krause-Glau]

Gradle enables users to use a "inheritance-alike" feature for the build.gradle file of a project. Essentially, this allows developers to provide seperated NAME.gradle files (so-called script plugins) that contain dependencies and tasks for a single topic, e.g., quality assurance.

To apply this feature, one has to use the apply from notation.

In addition with the new (Gradle 4.8) "TextResources can now be fetched from a URI" feature, we should be able to provide a so-called script plugin file for our quality assurance.

I tested this and with a small change to the SpotBugs plugin declaration and an updated version of the Gradle Wrapper (4.8), I was able to include a script plugin file based on our build.gradle.

Unfortunately, Gradle 4.8 is not yet supported by default in the Eclipse Buildship Plugin. We might be able to update the Buildship Plugin ourselves via http://download.eclipse.org/buildship/updates/e48/releases/ and use this overall awesome feature for quality assurance.

P.S. Checkstyle suppression are not possible to be outsourced via URL due to the Checkstyle implementation. Therefore, the checkstyle-suppression.xml is still required per project. This is not bad, since the suppression should be project dependent.

PMD however uses an embedded exclude/include approach in the pmd.xml file. This is a problem, since we cannot allow project dependent excludes. Is there a workaorund, such as using a further file for PMD exclude/includes?