Downloaded LWJGL libraries

- LWJGL is no longer shaded into the Bukkit jar
- plugin.yml lists the LWJGL jars and Linux natives as Spigot libraries
- The Paper loader resolves the same plugin.yml list through the Maven Central mirror
- The packed payload no longer reserves the LWJGL natives prefix
- Tests cover reading the library list from the plugin jar

adapters/bukkit/plugin/src/main/java/art/arcane/iris/IrisPluginLoader.java

@@ -6,12 +6,22 @@ import io.papermc.paper.plugin.bootstrap.PluginProviderContext;
 import io.papermc.paper.plugin.loader.PluginClasspathBuilder;
 import io.papermc.paper.plugin.loader.PluginLoader;
 import io.papermc.paper.plugin.loader.library.impl.JarLibrary;
+import io.papermc.paper.plugin.loader.library.impl.MavenLibraryResolver;
+import org.bukkit.configuration.file.YamlConfiguration;
+import org.eclipse.aether.artifact.DefaultArtifact;
+import org.eclipse.aether.graph.Dependency;
+import org.eclipse.aether.repository.RemoteRepository;
 
 import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.List;
 import java.util.stream.Stream;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipFile;
 
 @SuppressWarnings("UnstableApiUsage")
 public final class IrisPluginLoader implements PluginLoader {
@@ -40,6 +50,21 @@ public final class IrisPluginLoader implements PluginLoader {
                 classpathBuilder.addLibrary(new JarLibrary(library));
             }
         }
+        classpathBuilder.addLibrary(mavenResolver(mavenLibraries(context.getPluginSource())));
+    }
+
+    static List<String> mavenLibraries(Path pluginJar) {
+        try (ZipFile jar = new ZipFile(pluginJar.toFile())) {
+            ZipEntry descriptor = jar.getEntry("plugin.yml");
+            if (descriptor == null) {
+                throw new IllegalStateException("The Iris jar " + pluginJar + " has no plugin.yml library list.");
+            }
+            try (Reader reader = new InputStreamReader(jar.getInputStream(descriptor), StandardCharsets.UTF_8)) {
+                return YamlConfiguration.loadConfiguration(reader).getStringList("libraries");
+            }
+        } catch (IOException failure) {
+            throw new IllegalStateException("Unable to read the Iris library list from " + pluginJar + ".", failure);
+        }
     }
 
     static List<Path> relocatedLibraries(Path libraryRoot) {
@@ -59,6 +84,16 @@ public final class IrisPluginLoader implements PluginLoader {
         }
     }
 
+    private static MavenLibraryResolver mavenResolver(List<String> coordinates) {
+        MavenLibraryResolver resolver = new MavenLibraryResolver();
+        resolver.addRepository(new RemoteRepository.Builder("central", "default",
+                MavenLibraryResolver.MAVEN_CENTRAL_DEFAULT_MIRROR).build());
+        for (String coordinate : coordinates) {
+            resolver.addDependency(new Dependency(new DefaultArtifact(coordinate), null));
+        }
+        return resolver;
+    }
+
     private static boolean isRelocatedLibrary(Path path) {
         int count = path.getNameCount();
         for (int i = 0; i < count - 2; i++) {

adapters/bukkit/plugin/src/main/resources/plugin.yml

@@ -27,3 +27,4 @@ permissions:
     description: Allows survival players to fell Iris-managed trees with an axe.
     default: op
 api-version: '${apiVersion}'
+libraries: [ ${libraries} ]

adapters/bukkit/plugin/src/test/java/art/arcane/iris/IrisPluginLoaderTest.java

@@ -4,9 +4,13 @@ import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.TemporaryFolder;
 
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.List;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipOutputStream;
 
 import static org.junit.Assert.assertEquals;
 
@@ -31,4 +35,19 @@ public class IrisPluginLoaderTest {
 
         assertEquals(List.of(relocatedCaffeine, relocatedGson), libraries);
     }
+
+    @Test
+    public void readsMavenLibrariesFromTheSpigotDescriptorInThePluginJar() throws Exception {
+        Path jar = temporaryFolder.getRoot().toPath().resolve("Iris.jar");
+        try (OutputStream file = Files.newOutputStream(jar); ZipOutputStream zip = new ZipOutputStream(file)) {
+            zip.putNextEntry(new ZipEntry("plugin.yml"));
+            zip.write("name: Iris\nlibraries: [ 'org.lwjgl:lwjgl:3.4.3', 'org.lwjgl:lwjgl:jar:natives-linux:3.4.3' ]\n"
+                    .getBytes(StandardCharsets.UTF_8));
+            zip.closeEntry();
+        }
+
+        List<String> libraries = IrisPluginLoader.mavenLibraries(jar);
+
+        assertEquals(List.of("org.lwjgl:lwjgl:3.4.3", "org.lwjgl:lwjgl:jar:natives-linux:3.4.3"), libraries);
+    }
 }