public List<Token> getHiddenTokensToRight(int tokenIndex, int channel) {
		lazyInit();
		if ( tokenIndex<0 || tokenIndex>=tokens.size() ) {
			throw new IndexOutOfBoundsException(tokenIndex+" not in 0.."+(tokens.size()-1));
		}

		int nextOnChannel =
			nextTokenOnChannel(tokenIndex + 1, Lexer.DEFAULT_TOKEN_CHANNEL);
		int to;
		int from = tokenIndex+1;
		// if none onchannel to right, nextOnChannel=-1 so set to = last token
		if ( nextOnChannel == -1 ) to = size()-1;
		else to = nextOnChannel;

		return filterForChannel(from, to, channel);
	}
Collect all tokens on specified channel to the right of
 the current token up until we see a token on DEFAULT_TOKEN_CHANNEL or
 EOF. If channel is -1, find any non default channel token.
runtime/Java/src/org/antlr/v4/runtime/BufferedTokenStream.java