private String readString() {
        if (isQuoteCharacter(peek())) {
            return readQuotedString();
        } else {
            return readUnquotedString();
        }
    }
Tokenizes strings on whitespace, but ignoring whitespace enclosed within quotes.
common/src/main/java/me/lucko/luckperms/common/command/utils/QuotedStringTokenizer.java