AnnotationRemover.java

import org.objectweb.asm.*;

import java.io.FileOutputStream;
import java.util.Collections;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.jar.JarOutputStream;

public class AnnotationRemover {
    private static final String INPUT = "remapped.jar";
    private static final String OUTPUT = "remapped-no-annotations.jar";

    public static void main(String[] args) throws Exception {
        try (JarFile fromJar = new JarFile(INPUT);
             JarOutputStream outputJar = new JarOutputStream(new FileOutputStream(OUTPUT))) {
            for (JarEntry entry : Collections.list(fromJar.entries())) {
                if (!entry.getName().endsWith(".class")) {
                    continue;
                }

                ClassWriter classWriter = new ClassWriter(0);
                new ClassReader(fromJar.getInputStream(entry)).accept(new ClassVisitor(Opcodes.ASM7, classWriter) {
                    @Override
                    public AnnotationVisitor visitAnnotation(String descriptor, boolean visible) {
                        return descriptor.startsWith("Lnet/fabricmc") ? null : super.visitAnnotation(descriptor, visible);
                    }
                }, 0);

                outputJar.putNextEntry(new JarEntry(entry.getName()));
                outputJar.write(classWriter.toByteArray());
            }
        }
    }
}