Experimental bump of BungeeCord module to Java 17

Java 17+ and 21 are LTS releases. The other proxy Velocity
also includes Java 17. Ubuntu 24 LTS includes Java 21 already.
However, Ubuntu 22 LTS only uses Java 11, so it might be
necessary to fallback although Ubuntu 23 includes it.
Nevertheless, third-party JDK installations are also a thing
and Minecraft 1.20.6 nowadays also requires Java 21.

README.md

@@ -60,7 +60,9 @@ Possible values: `Premium`, `Cracked`, `Unknown`
 
 ## Requirements
 
-* Java 8 supported, but Java 21+ recommended for improved threading
+* Java: 21+ recommended for improved multi-threading code by FastLogin
+  * Spigot: 8+
+  * BungeeCord and Velocity: 17+
 * Server software in offlinemode:
   * Spigot (or a fork e.g. Paper) 1.8.8+
     * Protocol plugin:

bungee/pom.xml

@@ -41,7 +41,7 @@
     <packaging>jar</packaging>
 
     <properties>
-        <maven.compiler.release>8</maven.compiler.release>
+        <maven.compiler.release>17</maven.compiler.release>
     </properties>
 
     <!--Represents the main plugin-->