#vulnerable code 
                                @Override
    public Swagger read(Set<Class<?>> classes) throws GenerateException {
        //relate all methods to one base request mapping if multiple controllers exist for that mapping
        //get all methods from each controller & find their request mapping
        //create map - resource string (after first slash) as key, new SpringResource as value
        Map<String, SpringResource> resourceMap =  generateResourceMap(classes);
        for (String str : resourceMap.keySet()) {
            SpringResource resource = resourceMap.get(str);
            swagger = read(resource);
        }

        return swagger;
    } 
                            #location 9 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    public Swagger read(Set<Class<?>> classes) throws GenerateException {
        //relate all methods to one base request mapping if multiple controllers exist for that mapping
        //get all methods from each controller & find their request mapping
        //create map - resource string (after first slash) as key, new SpringResource as value
        Map<String, SpringResource> resourceMap = generateResourceMap(classes);
        for (String str : resourceMap.keySet()) {
            SpringResource resource = resourceMap.get(str);
            read(resource);
        }

        return swagger;
    }