#vulnerable code 
                                public Operation parseMethod(String httpMethod, Method method) {
        int responseCode = 200;
        Operation operation = new Operation();
        ApiOperation apiOperation = AnnotationUtils.findAnnotation(method, ApiOperation.class);

        String operationId = getOperationId(method, httpMethod);

        String responseContainer = null;

        Type responseClassType = null;
        Map<String, Property> defaultResponseHeaders = null;

        if (apiOperation != null) {
            if (apiOperation.hidden()) {
                return null;
            }
            if (!apiOperation.nickname().isEmpty()) {
                operationId = apiOperation.nickname();
            }

            defaultResponseHeaders = parseResponseHeaders(apiOperation.responseHeaders());
            operation.summary(apiOperation.value()).description(apiOperation.notes());

            Map<String, Object> customExtensions = BaseReaderUtils.parseExtensions(apiOperation.extensions());
            operation.setVendorExtensions(customExtensions);

            if (!apiOperation.response().equals(Void.class) && !apiOperation.response().equals(void.class)) {
                responseClassType = apiOperation.response();
            }
            if (!apiOperation.responseContainer().isEmpty()) {
                responseContainer = apiOperation.responseContainer();
            }
            List<SecurityRequirement> securities = new ArrayList<>();
            for (Authorization auth : apiOperation.authorizations()) {
                if (!auth.value().isEmpty()) {
                    SecurityRequirement security = new SecurityRequirement();
                    security.setName(auth.value());
                    for (AuthorizationScope scope : auth.scopes()) {
                        if (!scope.scope().isEmpty()) {
                            security.addScope(scope.scope());
                        }
                    }
                    securities.add(security);
                }
            }

            for (SecurityRequirement sec : securities) {
                operation.security(sec);
            }
        }
        operation.operationId(operationId);

        if (responseClassType == null) {
            // pick out response from method declaration
            LOGGER.debug("picking up response class from method " + method);
            responseClassType = method.getGenericReturnType();
        }
        boolean hasApiAnnotation = false;
        if (responseClassType instanceof Class) {
            hasApiAnnotation = AnnotationUtils.findAnnotation((Class) responseClassType, Api.class) != null;
        }
        if ((responseClassType != null)
                && !responseClassType.equals(Void.class)
                && !responseClassType.equals(void.class)
                && !responseClassType.equals(javax.ws.rs.core.Response.class)
                && !hasApiAnnotation
                && !isSubResource(httpMethod, method)) {
            if (isPrimitive(responseClassType)) {
                Property property = ModelConverters.getInstance().readAsProperty(responseClassType);
                if (property != null) {
                    Property responseProperty = RESPONSE_CONTAINER_CONVERTER.withResponseContainer(responseContainer, property);

                    operation.response(responseCode, new Response()
                            .description("successful operation")
                            .schema(responseProperty)
                            .headers(defaultResponseHeaders));
                }
            } else if (!responseClassType.equals(Void.class) && !responseClassType.equals(void.class)) {
                Map<String, Model> models = readModels(responseClassType);
                if (models.isEmpty()) {
                    Property p = ModelConverters.getInstance().readAsProperty(responseClassType);
                    operation.response(responseCode, new Response()
                            .description("successful operation")
                            .schema(p)
                            .headers(defaultResponseHeaders));
                }
                for (String key : models.keySet()) {
                    Property responseProperty = RESPONSE_CONTAINER_CONVERTER.withResponseContainer(responseContainer, new RefProperty().asDefault(key));


                    operation.response(responseCode, new Response()
                            .description("successful operation")
                            .schema(responseProperty)
                            .headers(defaultResponseHeaders));
                    swagger.model(key, models.get(key));
                }
            }
            Map<String, Model> models = readAllModels(responseClassType);
            for (Map.Entry<String, Model> entry : models.entrySet()) {
                swagger.model(entry.getKey(), entry.getValue());
            }
        }

        Consumes consumes = AnnotationUtils.findAnnotation(method, Consumes.class);
        if (consumes != null) {
            for (String mediaType : consumes.value()) {
                operation.consumes(mediaType);
            }
        }

        Produces produces = AnnotationUtils.findAnnotation(method, Produces.class);
        if (produces != null) {
            for (String mediaType : produces.value()) {
                operation.produces(mediaType);
            }
        }

        ApiResponses responseAnnotation = AnnotationUtils.findAnnotation(method, ApiResponses.class);
        if (responseAnnotation != null) {
            updateApiResponse(operation, responseAnnotation);
        }

        if (AnnotationUtils.findAnnotation(method, Deprecated.class) != null) {
            operation.deprecated(true);
        }

        // process parameters
        Class<?>[] parameterTypes = method.getParameterTypes();
        Type[] genericParameterTypes = method.getGenericParameterTypes();
        Annotation[][] paramAnnotations = findParamAnnotations(method);

        for (int i = 0; i < parameterTypes.length; i++) {
            Type type = genericParameterTypes[i];
            List<Annotation> annotations = Arrays.asList(paramAnnotations[i]);
            List<Parameter> parameters = getParameters(type, annotations);

            for (Parameter parameter : parameters) {
                if (hasCommonParameter(parameter)) {
                    Parameter refParameter = new RefParameter(RefType.PARAMETER.getInternalPrefix() + parameter.getName());
                    operation.parameter(refParameter);
                } else {
                    parameter = replaceArrayModelForOctetStream(operation, parameter);
                    operation.parameter(parameter);
                }
            }
        }
        if (operation.getResponses() == null) {
            operation.defaultResponse(new Response().description("successful operation"));
        }

        // Process @ApiImplicitParams
        this.readImplicitParameters(method, operation);

        processOperationDecorator(operation, method);

        return operation;
    } 
                            #location 80 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public Operation parseMethod(String httpMethod, Method method) {
        int responseCode = 200;
        Operation operation = new Operation();
        ApiOperation apiOperation = AnnotationUtils.findAnnotation(method, ApiOperation.class);

        String operationId = getOperationId(method, httpMethod);

        String responseContainer = null;

        Type responseClassType = null;
        Map<String, Property> defaultResponseHeaders = null;

        if (apiOperation != null) {
            if (apiOperation.hidden()) {
                return null;
            }
            if (!apiOperation.nickname().isEmpty()) {
                operationId = apiOperation.nickname();
            }

            defaultResponseHeaders = parseResponseHeaders(apiOperation.responseHeaders());
            operation.summary(apiOperation.value()).description(apiOperation.notes());

            Map<String, Object> customExtensions = BaseReaderUtils.parseExtensions(apiOperation.extensions());
            operation.setVendorExtensions(customExtensions);

            if (!apiOperation.response().equals(Void.class) && !apiOperation.response().equals(void.class)) {
                responseClassType = apiOperation.response();
            }
            if (!apiOperation.responseContainer().isEmpty()) {
                responseContainer = apiOperation.responseContainer();
            }
            List<SecurityRequirement> securities = new ArrayList<>();
            for (Authorization auth : apiOperation.authorizations()) {
                if (!auth.value().isEmpty()) {
                    SecurityRequirement security = new SecurityRequirement();
                    security.setName(auth.value());
                    for (AuthorizationScope scope : auth.scopes()) {
                        if (!scope.scope().isEmpty()) {
                            security.addScope(scope.scope());
                        }
                    }
                    securities.add(security);
                }
            }

            for (SecurityRequirement sec : securities) {
                operation.security(sec);
            }
        }
        operation.operationId(operationId);

        if (responseClassType == null) {
            // pick out response from method declaration
            LOGGER.debug("picking up response class from method " + method);
            responseClassType = method.getGenericReturnType();
        }
        boolean hasApiAnnotation = false;
        if (responseClassType instanceof Class) {
            hasApiAnnotation = AnnotationUtils.findAnnotation((Class) responseClassType, Api.class) != null;
        }
        if ((responseClassType != null)
                && !responseClassType.equals(Void.class)
                && !responseClassType.equals(void.class)
                && !responseClassType.equals(javax.ws.rs.core.Response.class)
                && !hasApiAnnotation
                && !isSubResource(httpMethod, method)) {
            if (isPrimitive(responseClassType)) {
                Property property = ModelConverters.getInstance().readAsProperty(responseClassType);
                if (property != null) {
                    Property responseProperty = RESPONSE_CONTAINER_CONVERTER.withResponseContainer(responseContainer, property);

                    operation.response(responseCode, new Response()
                            .description("successful operation")
                            .schema(responseProperty)
                            .headers(defaultResponseHeaders));
                }
            } else if (!responseClassType.equals(Void.class) && !responseClassType.equals(void.class)) {
                Map<String, Model> models = ModelConverters.getInstance().read(responseClassType);
                if (models.isEmpty()) {
                    Property p = ModelConverters.getInstance().readAsProperty(responseClassType);
                    operation.response(responseCode, new Response()
                            .description("successful operation")
                            .schema(p)
                            .headers(defaultResponseHeaders));
                }
                for (String key : models.keySet()) {
                    Property responseProperty = RESPONSE_CONTAINER_CONVERTER.withResponseContainer(responseContainer, new RefProperty().asDefault(key));


                    operation.response(responseCode, new Response()
                            .description("successful operation")
                            .schema(responseProperty)
                            .headers(defaultResponseHeaders));
                    swagger.model(key, models.get(key));
                }
            }
            Map<String, Model> models = readAllModels(responseClassType);
            for (Map.Entry<String, Model> entry : models.entrySet()) {
                swagger.model(entry.getKey(), entry.getValue());
            }
        }

        Consumes consumes = AnnotationUtils.findAnnotation(method, Consumes.class);
        if (consumes != null) {
            for (String mediaType : consumes.value()) {
                operation.consumes(mediaType);
            }
        }

        Produces produces = AnnotationUtils.findAnnotation(method, Produces.class);
        if (produces != null) {
            for (String mediaType : produces.value()) {
                operation.produces(mediaType);
            }
        }

        ApiResponses responseAnnotation = AnnotationUtils.findAnnotation(method, ApiResponses.class);
        if (responseAnnotation != null) {
            updateApiResponse(operation, responseAnnotation);
        }

        if (AnnotationUtils.findAnnotation(method, Deprecated.class) != null) {
            operation.deprecated(true);
        }

        // process parameters
        Class<?>[] parameterTypes = method.getParameterTypes();
        Type[] genericParameterTypes = method.getGenericParameterTypes();
        Annotation[][] paramAnnotations = findParamAnnotations(method);

        for (int i = 0; i < parameterTypes.length; i++) {
            Type type = genericParameterTypes[i];
            List<Annotation> annotations = Arrays.asList(paramAnnotations[i]);
            List<Parameter> parameters = getParameters(type, annotations);

            for (Parameter parameter : parameters) {
                if (hasCommonParameter(parameter)) {
                    Parameter refParameter = new RefParameter(RefType.PARAMETER.getInternalPrefix() + parameter.getName());
                    operation.parameter(refParameter);
                } else {
                    parameter = replaceArrayModelForOctetStream(operation, parameter);
                    operation.parameter(parameter);
                }
            }
        }
        if (operation.getResponses() == null) {
            operation.defaultResponse(new Response().description("successful operation"));
        }

        // Process @ApiImplicitParams
        this.readImplicitParameters(method, operation);

        processOperationDecorator(operation, method);

        return operation;
    }