Adopt latest version if different versions of same plugin are found

build.sbt

@@ -50,6 +50,7 @@ libraryDependencies ++= Seq(
   "org.cache2k"                     %  "cache2k-all"                  % "1.0.0.CR1",
   "com.enragedginger"               %% "akka-quartz-scheduler"        % "1.6.0-akka-2.4.x" exclude("c3p0","c3p0"),
   "net.coobird"                     %  "thumbnailator"                % "0.4.8",
+  "com.github.zafarkhaja"           %  "java-semver"                  % "0.9.0",
   "org.eclipse.jetty"               %  "jetty-webapp"                 % JettyVersion     % "provided",
   "javax.servlet"                   %  "javax.servlet-api"            % "3.1.0"          % "provided",
   "junit"                           %  "junit"                        % "4.12"           % "test",

src/main/scala/gitbucket/core/plugin/PluginRegistory.scala

@@ -21,6 +21,7 @@ import play.twirl.api.Html
 
 import scala.collection.mutable
 import scala.collection.mutable.ListBuffer
+import com.github.zafarkhaja.semver.Version
 
 class PluginRegistry {
 
@@ -197,7 +198,16 @@ object PluginRegistry {
     if(pluginDir.exists && pluginDir.isDirectory){
       pluginDir.listFiles(new FilenameFilter {
         override def accept(dir: File, name: String): Boolean = name.endsWith(".jar")
-      }).sortBy(_.getName).foreach { pluginJar =>
+      }).map { file =>
+        val Array(name, version) = file.getName.split("_2.12-")
+        (name, Version.valueOf(version.replaceFirst("\\.jar$", "")), file)
+      }.groupBy { case (name, _, _) =>
+        name
+      }.map { case (name, versions) =>
+        // Adopt the latest version
+        versions.sortBy { case (name, version, file) => version }.reverse.head._3
+      }.toSeq.sortBy(_.getName).foreach { pluginJar =>
+        logger.info(s"Initialize ${pluginJar.getName}")
         val classLoader = new URLClassLoader(Array(pluginJar.toURI.toURL), Thread.currentThread.getContextClassLoader)
         try {
           val plugin = classLoader.loadClass("Plugin").getDeclaredConstructor().newInstance().asInstanceOf[Plugin]
@@ -222,7 +232,6 @@ object PluginRegistry {
             description   = plugin.description,
             pluginClass   = plugin
           ))
-
         } catch {
           case e: Throwable => {
             logger.error(s"Error during plugin initialization: ${pluginJar.getAbsolutePath}", e)