* If buildUnicodeString() is called after build(), the trie will be
* re-serialized into a new array.
* If build() is called after buildUnicodeString(), the trie object will become
* the owner of the previously returned array.
* After clear() has been called, a new array will be used as well.
* @param buildOption Build option, see UStringTrieBuildOption.
* If buildUnicodeString() is called after build(), the trie will be
* re-serialized into a new array.
* If build() is called after buildUnicodeString(), the trie object will become
* the owner of the previously returned array.
* After clear() has been called, a new array will be used as well.
* @param buildOption Build option, see UStringTrieBuildOption.