title: Spring SPEL expression, access nested interface String constants
body: <p>i use nested interfaces to store String constants :</p>
  
  <pre><code>public interface Constants{
      interface level1 {
          interface level2 {
              String CONSTANT = "constant";
          }
      }
  }
  </code></pre>
  
  <p>I want to inject these constants into a spring value field, i have tried :</p>
  
  <pre><code> &lt;entry key="key" value="#{com.company.Constants.level1.level2.CONSTANT}"/&gt;
   &lt;entry key="key" value="#{T(com.company.Constants.level1.level2).CONSTANT}"/&gt;
  </code></pre>
  
  <p>But it's not working, what is the proper way ?</p>