Thread: Collect all words in a Trie with a prefix

I'm trying to implement a method that will store all words in a Trie data structure in a List.
This is my Node class:

class Node {
    char c;
    HashMap<Character, Node> children = new HashMap<Character, Node>();
    boolean isCompleteWord;
 
    public Node(char c) {
        this.c = c;
        isCompleteWord = false;
    }
    public Node() {
    }
}

I am using a HashMap to store the child characters as keys and the child nodes as values. A node that completes a word will have the field isCompleteWord set to true.

Methods to add all words to a List:

List<String> collectWords(char c) {
    List<String> words = new ArrayList<>();
    String word = Character.toString(c);
    Node node = root.children.get(c);
    collectWordsHelper(words, node, word);
    return words;
}
 
void collectWordsHelper(List<String> words, Node node, String word) {
    for (char i = 'a'; i <= 'z'; i++) {
        if (node.children.containsKey(i)) {
            System.out.println(i); // prints the right letters
            Node child = node.children.get(i);
            word += i;
            if (child.isCompleteWord && !words.contains(word)) {
                words.add(word);
                collectWordsHelper(words, child, "");
            }
            collectWordsHelper(words, child, word);
        }
    }
}

Currently if I have stored in the Trie the words "beard", "bold", "brew", when I print the list of words starting with the prefix "b", I get:

[beard, beold, beorew]

What I was expecting

[beard, bold, brew]

I think I need a way for the String word to be reset whenever I have found a word, instead of the next characters being appended.