src/Collection/Taxonomy/Vocabulary.php
public function add(ItemInterface $item)
    {
        if ($this->has($item->getId())) {
            // return if already exists
            return $this;
        }
        $this->items[$item->getId()] = $item;

        return $this;
    }
public function add(ItemInterface $item)
    {
        if ($this->has($item->getId())) {
            // return if already exists
            return $this;
        }
        $this->items[$item->getId()] = $item;

        return $this;
    }
Adds term to a Vocabulary collection.
{@inheritdoc}