title: What is purpose of @ConditionalOnProperty annotation?
body: <p>I just modified spring boot configuration, and encountered </p>
  
  <pre><code>@ConditionalOnProperty(prefix = "spring.social.", value = "auto-connection-views") 
  </code></pre>
  
  <p>from <code>org.springframework.boot.autoconfigure.social.TwitterAutoConfiguration</code></p>
  
  <pre><code>@Bean(name = { "connect/twitterConnect", "connect/twitterConnected" })
  @ConditionalOnProperty(prefix = "spring.social.", value = "auto-connection-views")
  public View twitterConnectView() {
      return new GenericConnectionStatusView("twitter", "Twitter");
  }
  </code></pre>
  
  <p>I don't understand purpose of this annotation. I guess this might be enable to use bean only if property  value exist(e.g. "spring.social", "auto-connection-views").</p>