Automate version updates

Currently the updating process of the hivemq projects involves
checking out every project independently and updating their version in
the gradle.properties file.

To mitigate this repetitive manual work, we introduce the plugins
project with a first Gradle plugin, which updates this version
automatically to the version set in the hivemq project & commits and
pushes the updated versions to the remote-tracking branch.

As the open-source projects should still work as before, the plugins are
only applied optionally, so that contributors do not need the plugins
project.

Furthermore, custom files, in which the current version should also be
updated can be defined via
`project.ext.set("versionUpdaterFiles", files("myFile"))`.

Added Gradle tasks: updateVersion, publishNewVersion

Resolves 1259

Author: gitseti

build.gradle.kts

@@ -1,3 +1,11 @@
+buildscript {
+    dependencies {
+        if (gradle.includedBuilds.find { it.name == "plugins"} != null) {
+            classpath("com.hivemq:plugins")
+        }
+    }
+}
+
 plugins {
     id("java-library")
     id("maven-publish")
@@ -9,6 +17,11 @@ plugins {
     id("com.github.sgtsilvio.gradle.javadoc-links")
 }
 
+if (gradle.includedBuilds.find { it.name == "plugins"} != null) {
+    apply(plugin = "com.hivemq.version-updater")
+    project.ext.set("versionUpdaterFiles", files("README.adoc"))
+}
+
 
 /* ******************** metadata ******************** */
 

settings.gradle.kts

@@ -13,5 +13,8 @@ pluginManagement {
 if (file("../hivemq-extension-sdk").exists()) {
     includeBuild("../hivemq-extension-sdk")
 }
+if (file("../plugins").exists()) {
+    includeBuild("../plugins")
+}
 
 includeBuild("../hivemq-platform")