code: private static Method resolveMethod(Class<? extends Handler> handler_class, String handler_method) {
      for (Method method : handler_class.getMethods())
        if (method.getName().equals(handler_method)) {
          Class[] pt = method.getParameterTypes();
          if (pt != null && pt.length == 2 && pt[0] == Integer.TYPE && Schema.class.isAssignableFrom(pt[1]))
            return method;
        }
      throw H2O.fail("Failed to find handler method: " + handler_method + " in class: " + handler_class.getSimpleName());
    }
docs: Search the provided class (and all its superclasses) for the requested method.
  @param handler_class Class to be searched
  @param handler_method Name of the method to look for. The method must have signature (int, Schema).
  @return The callable Method object.