Using spring managed beans in a default method of an interface?

Question

Warning. I understand that this may be an abuse of intent regarding the default beans beans and / or Java 8 interface methods. I am looking for concrete and reasoned criticism of why this might be an unsafe approach that I do not recognize.

I defined a class that gives me static access to the context of a running application:

@Component
public class BeanAccessor implements ApplicationContextAware {

    private static ApplicationContext applicationContext;

    public static <T> T getSingleton(Class<T> clazz){
        return applicationContext.getBean(clazz);
    }

    public static <T> T getSingleton(String beanName, Class<T> clazz){
        return applicationContext.getBean(beanName, clazz);
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        BeanAccessor.applicationContext = applicationContext;
    }

}

Then I can use these BeanAccessor methods inside the default interface methods to access spring managed beans inside the method.

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:

public interface ClientAware {

    String TENANT_NAME = "TENANT_NAME";

    default ClientDetails clientDetails() {
        ClientDetailsService service = BeanAccessor.getSingleton(ClientDetailsService.class);
        return service.loadClientByClientId(SecurityUtil.getClientId());
    }

    default Map<String, Object> clientInfo() {
        return clientDetails().getAdditionalInformation();
    }

    default String tenant() {
        return (String) clientInfo().get(TENANT_NAME);
    }

}

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@RestController
@RequestMapping("/documents")
public class Documents implements WrapAware, ClientAware {

        @Autowired
        private DocumentService docService;

        @RequestMapping(method = RequestMethod.GET)
        public Object byPathAndTenant(@RequestParam("path") String path) {
            return ok(docService.getDocumentsByPathAndTenant(path, tenant()));
        }

}

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Answer 1

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