public static String getPackageName(Class<?> cls) {
        if (cls == null) {
            return StringUtils.EMPTY;
        }
        return getPackageName(cls.getName());
    }
<p>Gets the package name of a {@code Class}.</p>

@param cls  the class to get the package name for, may be {@code null}.
@return the package name or an empty string
android/android_framework/base/src/main/java/lang3/ClassUtils.java