title: Spring placeholder doesn't resolve properties in JavaConfig
body: <p>Currently i have a Spring xml configuration (Spring 4) which load a properties file. </p>
  
  <p>context.properties</p>
  
  <pre><code>my.app.service = myService
  my.app.other = ${my.app.service}/sample
  </code></pre>
  
  <p>Spring xml configuration </p>
  
  <pre><code>&lt;bean id="contextProperties" class="org.springframework.beans.factory.config.PropertiesFactoryBean"&gt;
      &lt;property name="ignoreResourceNotFound" value="true" /&gt;
      &lt;property name="fileEncoding" value="UTF-8" /&gt;
      &lt;property name="locations"&gt;
          &lt;list&gt;
              &lt;value&gt;classpath:context.properties&lt;/value&gt;
          &lt;/list&gt;
      &lt;/property&gt;
  &lt;/bean&gt;
  &lt;bean id="placeholder" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"&gt;
      &lt;property name="ignoreResourceNotFound" value="true" /&gt;
      &lt;property name="properties" ref="contextProperties" /&gt;
      &lt;property name="nullValue" value="@null" /&gt;
      &lt;property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" /&gt;
  &lt;/bean&gt;
  </code></pre>
  
  <p>Bean which use the properties </p>
  
  <pre><code>@Component
  public class MyComponent {
  
      @Value("${my.app.other}")
      private String others;
  
  }
  </code></pre>
  
  <p>This works perfectly and the <code>others</code> value is <code>MyService/sample</code>, as excepted. But when i try to replace this configuration by a JavaConfig, the <code>@Value</code> in my component doesn't works in the same way. the value isn't <code>myService/sample</code> but <code>${my.app.service}/sample</code>.</p>
  
  <pre><code>@Configuration
  @PropertySource(name="contextProperties", ignoreResourceNotFound=true, value={"classpath:context.properties"})
  public class PropertiesConfiguration {
  
      @Bean
      public static PropertyPlaceholderConfigurer placeholder() throws IOException {
          PropertyPlaceholderConfigurer placeholder = new PropertyPlaceholderConfigurer();
          placeholder.setNullValue("@null");
          placeholder.setSystemPropertiesMode(PropertyPlaceholderConfigurer.SYSTEM_PROPERTIES_MODE_OVERRIDE);
          return placeholder;
      }
  
  }
  </code></pre>
  
  <p>Did i miss something in the conversion from xml to Javaconfig ?</p>
  
  <p>ps : I also try to instantiate a <code>PropertySourcesPlaceholderConfigurer</code> instead of a <code>PropertyPlaceholderConfigurer</code> without more success. </p>