title: Use Java 1.4 for compilation in Ant
body: <p>I have some old Java source code that raises an error in ant. </p>
  
  <pre><code>[javac]             Enumeration enum = props.propertyNames();
  [javac]                         ^
  [javac]   (use -source 1.4 or lower to use 'enum' as an identifier)
  </code></pre>
  
  <p>How can I teach ANT to use <code>-source 1.4</code>?</p>