code: public static Method[] methodsDeclaredIn(final Class<?> cls, final Class<?>... additionalClasses) {
          if (cls == null) {
              throw new IllegalArgumentException("You need to supply at least one class.");
          }
          Set<Method> methods = new HashSet<Method>();
          methods.addAll(asList(WhiteboxImpl.getAllMethods(cls)));
          for (Class<?> klass : additionalClasses) {
              methods.addAll(asList(WhiteboxImpl.getAllMethods(klass)));
          }
          return methods.toArray(new Method[methods.size()]);
      }
docs: Get all methods in a class hierarchy of the supplied classes. Both
  declared an non-declared (no duplicates).
  
  @param cls
  The class whose methods to get.
  @param additionalClasses
  Additional classes whose methods to get.
  @return All methods declared in this class hierarchy.