Do you understand my BSTDictionary implementation?
/**
 * This class implements an ordered dictionary using a binary search tree.
 * It uses the BinarySearchTree class for the underlying implementation.
 */
public class BSTDictionary implements BSTDictionaryADT {
    private BinarySearchTree bst; // Instance of the BinarySearchTree

    /**
     * Constructor for the BSTDictionary class.
     */
    public BSTDictionary() {
        bst = new BinarySearchTree();
    }

    /**
     * Returns the Record with the given key k, or null if the Record is not in the dictionary.
     *
     * @param k The key of the Record to search for
     * @return The Record with the given key, or null if not found
     */
    public Record get(Key k) {
        BSTNode node = bst.get(bst.getRoot(), k);
        return (node != null) ? node.getRecord() : null;
    }

    /**
     * Inserts the given Record d into the ordered dictionary.
     * Throws a DictionaryException if a Record with the same Key as d is already in the dictionary.
     *
     * @param d The Record to be inserted
     * @throws DictionaryException If a Record with the same Key as d is already in the dictionary
     */
    public void put(Record d) throws DictionaryException {
        bst.insert(bst.getRoot(), d);
    }

    /**
     * Removes the Record with the given Key k from the dictionary.
     * Throws a DictionaryException if the Record is not in the dictionary.
     *
     * @param k The key of the Record to be removed
     * @throws DictionaryException If the Record is not in the dictionary
     */
    public void remove(Key k) throws DictionaryException {
        bst.remove(bst.getRoot(), k);
    }

    /**
     * Returns the successor of the given key k (the Record from the ordered dictionary with the smallest
     * Key larger than k); returns null if the given Key has no successor. The given Key DOES NOT need
     * to be in the dictionary.
     *
     * @param k The key for which the successor is to be found
     * @return The Record with the successor Key, or null if no successor exists
     */
    public Record successor(Key k) {
        BSTNode node = bst.successor(bst.getRoot(), k);
        return (node != null) ? node.getRecord() : null;
    }

    /**
     * Returns the predecessor of the given key k (the Record from the ordered dictionary with the largest
     * key smaller than k); returns null if the given Key has no predecessor. The given Key DOES NOT need
     * to be in the dictionary.
     *
     * @param k The key for which the predecessor is to be found
     * @return The Record with the predecessor Key, or null if no predecessor exists
     */
    public Record predecessor(Key k) {
        // Implement using the BinarySearchTree methods
        return null; // Placeholder
    }

    /**
     * Returns the Record with the smallest key in the ordered dictionary.
     * Returns null if the dictionary is empty.
     *
     * @return The Record with the smallest key, or null if the dictionary is empty
     */
    public Record smallest() {
        BSTNode node = bst.smallest(bst.getRoot());
        return (node != null) ? node.getRecord() : null;
    }

    /**
     * Returns the Record with the largest key in the ordered dictionary.
     * Returns null if the dictionary is empty.
     *
     * @return The Record with the largest key, or null if the dictionary is empty
     */
    public Record largest() {
        BSTNode node = bst.largest(bst.getRoot());
        return (node != null) ? node.getRecord() : null;
    }
}