title: add multiple cross origin urls in spring boot
body: <p>I found an example on how to set cors headers in spring-boot application. Since we have many origins, I need to add them. Is the following valid?</p>
  
  <pre><code>@Configuration
  @EnableWebMvc
  public class WebConfig extends WebMvcConfigurerAdapter {
  
      @Override
      public void addCorsMappings(CorsRegistry registry) {
          registry.addMapping("/api/**")
              .allowedOrigins("http://domain1.com")
              .allowedOrigins("http://domain2.com")
              .allowedOrigins("http://domain3.com")
      }
  }
  </code></pre>
  
  <p>I have no way to test this unless it is used by three domains. But I want to make sure I have three origins set up and not only "domain3.com" is set.</p>
  
  <p><strong>EDIT</strong>: ideal use case for is to inject a list of domains(from application.properties) and set that in allowedOrigins. Is it possible</p>
  
  <p>i.e</p>
  
  <pre><code>  @Value("${domainsList: not configured}")
      private List&lt;String&gt; domains;
  
  @Configuration
  @EnableWebMvc
  public class WebConfig extends WebMvcConfigurerAdapter {
  
      @Override
      public void addCorsMappings(CorsRegistry registry) {
          registry.addMapping("/api/**")
              .allowedOrigins(domains)
      }
  }
  </code></pre>