#vulnerable code 
                             public static void main(String... args) {

		RestTemplate template = new RestTemplate();

		HttpEntity<String> response = template.getForEntity(URI_TEMPLATE, String.class, MILESTONE_ID);

		boolean keepChecking = true;
		boolean printHeader = true;

		while (keepChecking) {

			readPage(response.getBody(), printHeader);
			printHeader = false;

			String linkHeader = response.getHeaders().get("Link").get(0);

			Links links = Arrays.stream(linkHeader.split(", ")) //
					.map(Link::valueOf) //
					.collect(Collectors.collectingAndThen(Collectors.toList(), Links::of));

			if (links.getLink(IanaLinkRelations.NEXT).isPresent()) {

				response = template.getForEntity(links.getRequiredLink(IanaLinkRelations.NEXT).expand().getHref(),
						String.class);

			} else {
				keepChecking = false;
			}
		}
	} 
                            #location 15 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                             public static void main(String... args) {

		/*
		 * If you run into github rate limiting issues, you can always use a Github Personal Token by adding
		 * {@code .header(HttpHeaders.AUTHORIZATION, "token your-github-token")} to the webClient call.
		 */

		WebClient webClient = WebClient.create();

		HttpEntity<String> response = webClient //
				.get().uri(URI_TEMPLATE, MILESTONE_ID) //
				.exchange() //
				.flatMap(clientResponse -> clientResponse.toEntity(String.class)) //
				.block(Duration.ofSeconds(10));

		boolean keepChecking = true;
		boolean printHeader = true;

		while (keepChecking) {

			readPage(response.getBody(), printHeader);
			printHeader = false;

			Links links = Links.parse(response.getHeaders().get(HttpHeaders.LINK).get(0));

			if (links.getLink(IanaLinkRelations.NEXT).isPresent()) {

				response = webClient //
						.get().uri(links.getRequiredLink(IanaLinkRelations.NEXT).expand().getHref()) //
						.exchange() //
						.flatMap(clientResponse -> clientResponse.toEntity(String.class)) //
						.block(Duration.ofSeconds(10));

			} else {
				keepChecking = false;
			}
		}
	}