sonar dynamic class loading issue

How could I fix sonnar issue delete dynamic class loading

protected Class registerAndLoadClass(String className) throws ClassNotFoundException {
        Class definedClass = classLoader.loadClass(className);
        addDefinedClass(definedClass, true, null);
        return definedClass;
    }

I tried

 protected Class registerAndLoadClass(String className) throws ClassNotFoundException {
        Class definedClass = null;
        try {
             definedClass = (Class) classLoader.getClass()
                    .getDeclaredMethod("loadClass", String.class, boolean.class)
                    .invoke(null, className);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
        addDefinedClass(definedClass, true, null);
        return definedClass;
    }

But it send NPE, when I'm trying to use it.