For the very first time, the full support for Java 8 features has been included. This version uses JavaEE6 as its baseline. Using Spring 4, now it is possible to define external bean configuration using Groovy DSL. Developers can now treat generic types as a form of qualifier. The @Lazy annotation can be used on injection points as well as on @Bean definitions. The @Description annotation has been introduced for developers using Java-based configuration. The @Conditional annotation has been introduced for conditional filtering. Now, there is no requirement to have a default constructor used by CGLIB-based proxy classes. The @RestController annotation has been introduced to remove the need of @ResponseBody to each of @RequestMapping. The AsynchRestTemplate has been included, which allows non-blocking asynchronous support for the REST client development. The spring-websocket module has been introduced as a new model to provide support for a WebSocket-based two-way communication between server and client. The spring-messaging module has been introduced for the support of WebSocket subprotocol, STOMP. Most of the annotations from the spring-test module can now be used as meta annotations to create custom-composed annotations. The set of mocks from org.springframework.mock.web is based on Servlet API 3.0.