In Spring Security, when a user needs multiple roles for accessing different resources, you can assign a composite role to the user. This composite role should include all the required roles for accessing those resources. Option 2 is not a recommended approach as it would lead to code duplication. Option 3 is a more complex solution and might not be necessary for this scenario. Option 4 is not an efficient way to handle role-based access control.

To customize the UserDetailsService in Spring Security to load user information from a different source, you should extend the UserDetailsService interface and override its methods to fetch user details from your desired source, such as a database or an external service. The other options do not accurately describe the standard way to customize the UserDetailsService.

To secure microservices using OAuth2 and JWT in a Spring Boot application, you can use an API Gateway as a central OAuth2 authorization server. This allows the API Gateway to authenticate and authorize requests to microservices using JWT tokens. Each microservice doesn't need its own authorization server, as this would be complex and harder to manage. Username and password-based authentication is not a recommended approach for microservices security. JWTs are suitable for securing microservices when used in conjunction with OAuth2 for access control.

In Spring Boot, the @ConfigurationProperties annotation is used to bind properties defined in the application properties file to a POJO (Plain Old Java Object). This allows you to map properties to fields in your Java class, providing a convenient way to access and manage configuration settings. The other annotations serve different purposes in Spring Boot, but @ConfigurationProperties is specifically designed for property binding.

Spring Cloud and Eureka work together for service discovery by adding the @EnableDiscoveryClient annotation to the Spring Boot application class. This annotation enables the application to register itself with the Eureka server and discover other services.

In Spring Boot, the "@Primary" annotation is used to designate a specific bean as the primary candidate for autowiring when there are multiple candidates for the same type. This is particularly useful when you have multiple beans of the same type, and you want to specify which one should be injected by default. The other options are related to autowiring but do not serve this specific purpose.

To customize the response body of a Spring Boot controller method, the @ResponseBody annotation is used. This annotation tells Spring that the return value of the method should be bound to the web response body, allowing you to customize the content that is sent back to the client. It's a key annotation for building RESTful web services with Spring Boot.

You can handle exceptions at the @RestController level by using @ExceptionHandler methods within the controller itself. This approach is different from using @ControllerAdvice, which is used for global exception handling across the application. @ControllerAdvice allows you to define exception handling methods that can be reused across multiple controllers, while @ExceptionHandler within the controller is specific to that controller.

To customize the token endpoint response of an OAuth2 Authorization Server in Spring Boot, you can create a custom OAuth2TokenEndpointConfigurer and configure it in the security configuration. Modifying the source code of the OAuth2 Authorization Server is not recommended for maintainability reasons. Using a filter in the client application is not the standard approach for customizing the token endpoint response.

The @SpringBootTest annotation is primarily used to start the Spring application context, which enables you to test your Spring Boot application in an integrated way. It loads the complete application context and allows you to interact with it during testing.