title: Environment variable expansion in persistence.xml (JPA)
body: <p>I am developing a Eclipse RCP plugin which uses JPA.
  I tried to specify the database path via a variable give to the JVM on runtime.
  The property is set correctly but the database is created in a folder named after the variable name (here: ${DBHOME}).</p>
  
  <pre><code>&lt;property name="javax.persistence.jdbc.url" value="jdbc:derby:${DBHOME};create=true"/&gt;
  </code></pre>
  
  <p>Is there a possibility to fix this?</p>
  
  <p>Thx</p>