void advance() {
        super.advance();
        if (tokens.isEmpty() && nesting() > 0) tokens.add(nextToken()); // Fill current token if needed and possible.
    }
A {@link TokenBuffer} which only buffers tokens when needed, i.e., when peeking.

@author jonmv
document/src/main/java/com/yahoo/document/json/LazyTokenBuffer.java