ArrayTrie getBest fails to match the empty string entry in certain cases

[lorban]

Jetty version(s)
9.4.x

Description

When an ArrayTrie contains an empty string, getBest() should always match it as a last resort. But when getBest() is given a key that starts with common letters but does not match an existing entry then null is returned instead of the empty string's value.

Consider the following:

ArrayTrie<Integer> trie = new ArrayTrie<>();

assertTrue(trie.put("", 0));
assertTrue(trie.put("prefix", 1));

assertEquals(0, trie.getBest("unknown"));
assertEquals(0, trie.getBest("pre-unknown")); // fails