* Multiple calls to buildStringPiece() return StringPieces referring to the
* builder's same byte array, without rebuilding.
* If buildStringPiece() is called after build(), the trie will be
* Multiple calls to buildStringPiece() return StringPieces referring to the
* builder's same byte array, without rebuilding.
* If buildStringPiece() is called after build(), the trie will be