Add source requirement to SkriptAddon

src/main/java/ch/njol/skript/Skript.java

@@ -496,7 +496,7 @@ public void onEnable() {
 		}
 
 		// initialize the modern Skript instance
-		skript = org.skriptlang.skript.Skript.of(this.getName());
+		skript = org.skriptlang.skript.Skript.of(getClass(), getName());
 		unmodifiableSkript = skript.unmodifiableView();
 		skript.localizer().setSourceDirectories(
 			getClass(),
@@ -1387,10 +1387,7 @@ public static Collection<SkriptAddon> getAddons() {
 		Set<SkriptAddon> addons = new HashSet<>(Skript.addons);
 		addons.addAll(instance().addons().stream()
 			.filter(addon -> addons.stream().noneMatch(oldAddon -> oldAddon.name().equals(addon.name())))
-			.flatMap(addon -> {
-				SkriptAddon old = SkriptAddon.fromModern(addon);
-				return old == null ? Stream.empty() : Stream.of(old);
-			})
+			.map(SkriptAddon::fromModern)
 			.collect(Collectors.toSet())
 		);
 		return Collections.unmodifiableCollection(addons);
@@ -1406,7 +1403,6 @@ public static Collection<SkriptAddon> getAddons() {
 	public static SkriptAddon getAddonInstance() {
 		if (addon == null) {
 			addon = SkriptAddon.fromModern(instance());
-			assert addon != null; // should never be null for Skript
 		}
 		return addon;
 	}

src/main/java/ch/njol/skript/SkriptAddon.java

@@ -51,7 +51,7 @@ public class SkriptAddon implements org.skriptlang.skript.addon.SkriptAddon {
 	 * Package-private constructor. Use {@link Skript#registerAddon(JavaPlugin)} to get a SkriptAddon for your plugin.
 	 */
 	SkriptAddon(JavaPlugin plugin) {
-		this(plugin, Skript.instance().registerAddon(plugin.getName()));
+		this(plugin, Skript.instance().registerAddon(plugin.getClass(), plugin.getName()));
 	}
 
 	SkriptAddon(JavaPlugin plugin, org.skriptlang.skript.addon.SkriptAddon addon) {
@@ -133,14 +133,14 @@ public File getFile() {
 	//
 
 	@ApiStatus.Experimental
-	static @Nullable SkriptAddon fromModern(org.skriptlang.skript.addon.SkriptAddon addon) {
-		Class<?> source = addon.localizer().source();
-		if (source != null) // using source would be most accurate
-			return new SkriptAddon(JavaPlugin.getProvidingPlugin(source), addon);
-		Plugin plugin = Bukkit.getServer().getPluginManager().getPlugin(addon.name());
-		if (!(plugin instanceof JavaPlugin))
-			return null;
-		return new SkriptAddon((JavaPlugin) plugin, addon);
+	static SkriptAddon fromModern(org.skriptlang.skript.addon.SkriptAddon addon) {
+		return new SkriptAddon(JavaPlugin.getProvidingPlugin(addon.source()), addon);
+	}
+
+	@Override
+	@ApiStatus.Experimental
+	public Class<?> source() {
+		return addon.source();
 	}
 
 	@Override

src/main/java/org/skriptlang/skript/Skript.java

@@ -16,20 +16,24 @@ public interface Skript extends SkriptAddon {
 	/**
 	 * Constructs a default implementation of a Skript.
 	 * It makes use of the default implementations of required components.
+	 * @param source The main class of the application creating this Skript.
+	 *  Typically, this can be the class invoking this method.
 	 * @param name The name for the Skript to use.
 	 * @return A Skript.
 	 */
-	@Contract("_ -> new")
-	static Skript of(String name) {
-		return new SkriptImpl(name);
+	@Contract("_, _ -> new")
+	static Skript of(Class<?> source, String name) {
+		return new SkriptImpl(source, name);
 	}
 
 	/**
 	 * Registers the provided addon with this Skript and loads the provided modules.
+	 * @param source The main class of the application registering this addon.
+	 *  Typically, this can be the class invoking this method.
 	 * @param name The name of the addon to register.
 	 */
-	@Contract("_ -> new")
-	SkriptAddon registerAddon(String name);
+	@Contract("_, _ -> new")
+	SkriptAddon registerAddon(Class<?> source, String name);
 
 	/**
 	 * @return An unmodifiable snapshot of addons currently registered with this Skript.

src/main/java/org/skriptlang/skript/SkriptImpl.java

@@ -24,8 +24,8 @@ final class SkriptImpl implements Skript {
 	 */
 	private final SkriptAddon addon;
 
-	SkriptImpl(String name) {
-		addon = new SkriptAddonImpl(this, name, Localizer.of(this));
+	SkriptImpl(Class<?> source, String name) {
+		addon = new SkriptAddonImpl(this, source, name, Localizer.of(this));
 		storeRegistry(SyntaxRegistry.class, SyntaxRegistry.empty());
 	}
 
@@ -72,17 +72,17 @@ public <R extends Registry<?>> R registry(Class<R> registryClass, Supplier<R> pu
 	private static final Set<SkriptAddon> addons = new HashSet<>();
 
 	@Override
-	public SkriptAddon registerAddon(String name) {
+	public SkriptAddon registerAddon(Class<?> source, String name) {
 		// make sure an addon is not already registered with this name
 		for (SkriptAddon addon : addons) {
 			if (name.equals(addon.name())) {
 				throw new SkriptAPIException(
-					"An addon (provided by '" + addon.getClass().getName() + "') with the name '" + name + "' is already registered"
+					"An addon (provided by '" + addon.source().getName() + "') with the name '" + name + "' is already registered"
 				);
 			}
 		}
 
-		SkriptAddon addon = new SkriptAddonImpl(this, name, null);
+		SkriptAddon addon = new SkriptAddonImpl(this, source, name, null);
 		addons.add(addon);
 		return addon;
 	}
@@ -96,6 +96,11 @@ public SkriptAddon registerAddon(String name) {
 	 * SkriptAddon Implementation
 	 */
 
+	@Override
+	public Class<?> source() {
+		return addon.source();
+	}
+
 	@Override
 	public String name() {
 		return addon.name();
@@ -119,15 +124,22 @@ public void loadModules(AddonModule... modules) {
 	private static final class SkriptAddonImpl implements SkriptAddon {
 
 		private final Skript skript;
+		private final Class<?> source;
 		private final String name;
 		private final Localizer localizer;
 
-		SkriptAddonImpl(Skript skript, String name, @Nullable Localizer localizer) {
+		SkriptAddonImpl(Skript skript, Class<?> source, String name, @Nullable Localizer localizer) {
 			this.skript = skript;
+			this.source = source;
 			this.name = name;
 			this.localizer = localizer == null ? Localizer.of(this) : localizer;
 		}
 
+		@Override
+		public Class<?> source() {
+			return source;
+		}
+
 		@Override
 		public String name() {
 			return name;
@@ -185,7 +197,7 @@ static final class UnmodifiableSkript implements Skript {
 		}
 
 		@Override
-		public SkriptAddon registerAddon(String name) {
+		public SkriptAddon registerAddon(Class<?> source, String name) {
 			throw new UnsupportedOperationException("Cannot register addons using an unmodifiable Skript");
 		}
 
@@ -198,6 +210,11 @@ public SkriptAddon registerAddon(String name) {
 			return addons.build();
 		}
 
+		@Override
+		public Class<?> source() {
+			return skript.source();
+		}
+
 		@Override
 		public String name() {
 			return skript.name();

src/main/java/org/skriptlang/skript/addon/AddonModule.java

@@ -12,7 +12,8 @@
 public interface AddonModule {
 
 	/**
-	 *
+	 * Used for loading the components (e.g. syntax) of this module.
+	 * Typically triggered through {@link SkriptAddon#loadModules(AddonModule...)}.
 	 * @param addon The addon this module belongs to.
 	 */
 	void load(SkriptAddon addon);

src/main/java/org/skriptlang/skript/addon/SkriptAddon.java

@@ -12,11 +12,17 @@
 
 /**
  * A Skript addon is an extension to Skript that expands its features.
- * Typically, an addon instance may be obtained through {@link Skript#registerAddon(String)}.
+ * Typically, an addon instance may be obtained through {@link Skript#registerAddon(Class, String)}.
  */
 @ApiStatus.Experimental
 public interface SkriptAddon extends ViewProvider<SkriptAddon> {
 
+	/**
+	 * @return A class from the application that registered this addon.
+	 * Typically, this is the main class or the specific class in which registration occurred.
+	 */
+	Class<?> source();
+
 	/**
 	 * @return The name of this addon.
 	 */

src/main/java/org/skriptlang/skript/addon/SkriptAddonImpl.java

@@ -19,6 +19,11 @@ static class UnmodifiableAddon implements SkriptAddon {
 			this.unmodifiableLocalizer = addon.localizer().unmodifiableView();
 		}
 
+		@Override
+		public Class<?> source() {
+			return addon.source();
+		}
+
 		@Override
 		public String name() {
 			return addon.name();