#vulnerable code 
                             public List<String> possibleHeaderNames(IContextMenuInvocation invocation) {
		IHttpRequestResponse[] selectedItems = invocation.getSelectedMessages();
		//byte selectedInvocationContext = invocation.getInvocationContext();
		Getter getter = new Getter(burp.callbacks.getHelpers());
		LinkedHashMap<String, String> headers = getter.getHeaderMap(true, selectedItems[0]);

		List<String> keywords = Arrays.asList(burp.tableModel.getConfigByKey("tokenHeaders").split(","));
		List<String> ResultHeaders = new ArrayList<String>();

		Iterator<String> it = headers.keySet().iterator();
		while (it.hasNext()) {
			String item = it.next();
			if (containOneOfKeywords(item,keywords,false)) {
				ResultHeaders.add(item);
			}
		}
		return ResultHeaders;
	} 
                            #location 7 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                             public List<String> possibleHeaderNames(IContextMenuInvocation invocation) {
		IHttpRequestResponse[] selectedItems = invocation.getSelectedMessages();
		//byte selectedInvocationContext = invocation.getInvocationContext();
		Getter getter = new Getter(burp.callbacks.getHelpers());
		LinkedHashMap<String, String> headers = getter.getHeaderMap(true, selectedItems[0]);

		List<String> keywords = Arrays.asList(burp.tableModel.getConfigValueByKey("tokenHeaders").split(","));
		List<String> ResultHeaders = new ArrayList<String>();

		Iterator<String> it = headers.keySet().iterator();
		while (it.hasNext()) {
			String item = it.next();
			if (containOneOfKeywords(item,keywords,false)) {
				ResultHeaders.add(item);
			}
		}
		return ResultHeaders;
	}