CakePHP 3：belongsToMany（通过）和其他关联

I have defined the following associations:

class RecipesTable extends Table
{
  $this->belongsToMany('Ingredients', [
    'through' => 'RecipesIngredients',
    'foreignKey' => 'recipe_id',
    'targetForeignKey' => 'ingredient_id',
  ]);

class IngredientsTable extends Table
{
  $this->belongsToMany('Recipes', [
    'through' => 'RecipesIngredients',
    'foreignKey' => 'ingredient_id',
    'targetForeignKey' => 'recipe_id',
  ]);

class RecipesIngredientsTable extends Table
{
  $this->belongsTo('Recipes');
  $this->belongsTo('Ingredients');
  $this->belongsTo('Units');

The table 'RecipesIngredients' has the following structure:

id | recipe_id | ingredient_id | unit_id | ...

Now I make a request like the one below to get Recipes and the associated Ingredients. But without the Units.

$data = $this->Recipe->find('all')
    ->where('Recipe.id' => 55)
    ->contain(['Ingredient', ...])
    ->all();

My question is: how do I get the data of the associated 'Units' in a call of $this->Recipe?

I tried different contains like ->contain(['Ingredient' => ['Unit'], ...]) (and so on) but this doesn't work. CakePHP just returns the associated ingredients and the contents of the 'through' join table without linking to the associated units. Or gives an error of missing associations.