Javassist throwing notfound / null pointer in CtMethod.make and getDeclaredMethod using OSGI

javassist is throwing null pointer in CtMethod.make com.company.test is the package of the Activator and Joe

public class Activator implements BundleActivator {

public Class<?> creerClasse() {
    CtClass toGenerateClass;
    ClassPool pool;
    pool = ClassPool.getDefault();
    try {
        Class c;
        c = Class.forName("com.company.test.Joe");
        pool.appendClassPath(new ClassClassPath(c));
    } catch (ClassNotFoundException e1) {
        e1.printStackTrace();
    }

    pool.importPackage("com.company.test");

    toGenerateClass = pool.makeClass("Test118");

    try {
        toGenerateClass
                .addMethod(CtMethod
                        .make("public void afficher (com.company.test.Joe msg) { System.out.println(msg); } ;",
                                toGenerateClass));
    } catch (CannotCompileException e) {
        e.printStackTrace();
    }

    try {
        return toGenerateClass.toClass();
    } catch (CannotCompileException e) {
        e.printStackTrace();
        return null;
    }
}


public void start(BundleContext context) throws Exception {


        Class<?> genClass = creerClasse();
        Class<?> c = Class.forName("com.company.test.Joe");

        for (Method me : genClass.getDeclaredMethods()) { // test print, ok
            System.out.println(me);
        }

        Method method = genClass.getDeclaredMethod("afficher", c);

        Joe person = new Joe();
        person.setId(17);
        method.invoke(genClass.newInstance(), person);

}

}

and when i instansiate pool with pool = new ClassPool(true); it throws java.lang.NoClassDefFoundError: com/company/test/Joe in getDeclaredMethod