Fix reading class aliases

Fixes #2263

src/main/java/com/comphenix/protocol/utility/CachedPackage.java

@@ -75,12 +75,6 @@ final class CachedPackage {
 		return source.loadClass(combine(packageName, className));
 	}
 
-	public Class<?> requireClass(String className) throws ClassNotFoundException {
-		String canonicalName = combine(packageName, className);
-		return source.loadClass(canonicalName)
-			.orElseThrow(() -> new ClassNotFoundException(className));
-	}
-
 	/**
 	 * Retrieve the class object of a specific class in the current package.
 	 *
@@ -96,7 +90,7 @@ final class CachedPackage {
 			}
 
 			for (String alias : aliases) {
-				clazz = resolveClass(className);
+				clazz = resolveClass(alias);
 				if (clazz.isPresent()) {
 					return clazz;
 				}

src/test/java/com/comphenix/protocol/utility/CachedPackageTest.java

@@ -0,0 +1,37 @@
+package com.comphenix.protocol.utility;
+
+import java.util.Optional;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class CachedPackageTest {
+	private CachedPackage pack;
+
+	@BeforeEach
+	public void prepare() {
+		ClassSource source = ClassSource.fromClassLoader();
+		this.pack = new CachedPackage("java.lang", source);
+	}
+
+	@Test
+	public void testGetPackageClass() {
+		Optional<Class<?>> result = pack.getPackageClass("Object");
+		assertTrue(result.isPresent());
+		assertEquals(result.get(), Object.class);
+	}
+
+	@Test
+	public void testUsingAliases() {
+		Optional<Class<?>> result = pack.getPackageClass("NOT_A_CLASS", "Object");
+		assertTrue(result.isPresent());
+		assertEquals(result.get(), Object.class);
+
+		result = pack.getPackageClass("NOT_A_CLASS", "STILL_NOT_A_CLASS", "Object");
+		assertTrue(result.isPresent());
+		assertEquals(result.get(), Object.class);
+	}
+}