Set version on build in sponge plugin

sponge/src/main/java/me/lucko/luckperms/LPSpongePlugin.java

@@ -37,9 +37,8 @@ import java.util.concurrent.TimeUnit;
 import java.util.stream.Collectors;
 
 @Getter
-@Plugin(id = "luckperms", name = "LuckPerms", version = LPSpongePlugin.VERSION, authors = {"Luck"}, description = "A permissions plugin")
+@Plugin(id = "luckperms", name = "LuckPerms", version = "MAGIC", authors = {"Luck"}, description = "A permissions plugin")
 public class LPSpongePlugin implements LuckPermsPlugin {
-    static final String VERSION = "1.5"; // TODO load this from pom
 
     @Inject
     private Logger logger;
@@ -142,7 +141,7 @@ public class LPSpongePlugin implements LuckPermsPlugin {
 
     @Override
     public String getVersion() {
-        return VERSION;
+        return "MAGIC";
     }
 
     @Override

sponge/src/main/java/me/lucko/luckperms/utils/VersionUtil.java

@@ -0,0 +1,45 @@
+package me.lucko.luckperms.utils;
+
+import de.icongmbh.oss.maven.plugin.javassist.ClassTransformer;
+import javassist.*;
+import javassist.bytecode.AnnotationsAttribute;
+import javassist.bytecode.annotation.Annotation;
+import javassist.bytecode.annotation.StringMemberValue;
+import me.lucko.luckperms.LPSpongePlugin;
+
+import java.util.Properties;
+
+/**
+ * Sets the version value of the plugin.
+ * Most of the code in this class was taken from:
+ * https://github.com/icon-Systemhaus-GmbH/javassist-maven-plugin/blob/master/README.textile
+ */
+public class VersionUtil extends ClassTransformer {
+    private String version = null;
+
+    @Override
+    protected boolean shouldTransform(CtClass clazz) throws NotFoundException {
+        CtClass pluginClass = ClassPool.getDefault().get(LPSpongePlugin.class.getName());
+        return !clazz.equals(pluginClass) && clazz.subtypeOf(pluginClass);
+    }
+
+    @Override
+    protected void applyTransformations(CtClass clazz) throws Exception {
+        AnnotationsAttribute attribute = (AnnotationsAttribute) clazz.getClassFile().getAttribute(AnnotationsAttribute.visibleTag);
+        Annotation annotation = attribute.getAnnotation("org.spongepowered.api.plugin.Plugin");
+        StringMemberValue versionValue = (StringMemberValue) annotation.getMemberValue("version");
+        versionValue.setValue(version);
+        attribute.setAnnotation(annotation);
+
+        CtMethod getVersionMethod = clazz.getDeclaredMethod("getVersion");
+        CtMethod hackedVersionMethod = CtNewMethod.make("public String getVersion() { return \"" + this.version + "\"; }", clazz);
+        clazz.removeMethod(getVersionMethod);
+        clazz.addMethod(hackedVersionMethod);
+    }
+
+    @Override
+    public void configure(final Properties properties) {
+        assert properties != null;
+        version = properties.getProperty("version");
+    }
+}