title: Conditional statement inside Spring config
body: <p>How to have conditional statement within a spring configuration file</p>
  
  <p>I have String bean (b) whose value depends on the value of a property (a). a is set dynamically based on environment it runs.</p>
  
  <pre><code>if (a)
   b="yes"
  else
   b="no"
  </code></pre>
  
  <p>How do i code this in spring config?</p>