title: Effect of enable-call-by-reference
body: <p>I get the messages</p>
  
  <pre><code>&lt;Warning&gt; &lt;EJB&gt; &lt;BEA-010202&gt; &lt;Call-by-reference is not enabled for the EJB 'myEjb'.
  The server will have better performance if it is enabled. To enable call-by-reference, set the enable-call-by-reference element to True in the weblogic-ejb-jar.xml deployment descriptor or corresponding annotation for this EJB.&gt;
  </code></pre>
  
  <p>and</p>
  
  <pre><code>&lt;Warning&gt; &lt;EJB&gt; &lt;BEA-012035&gt; &lt;The Remote interface method: 'public abstract java.util.Collection my.sessionfassade.ejb.myFassade.myMethod(java.lang.String,java.lang.String,java.util.Collection) throws my.Exception' in EJB 'myEjb' contains a parameter of type: 'java.util.Collection' which is not Serializable. Though the EJB 'myEjb' has call-by-reference set to false, this parameter is not Serializable and hence will be passed by reference. A parameter can be passed using call-by-value only if the parameter type is Serializable.&gt;
  </code></pre>
  
  <p>Why would this not be enabled by default, as remote calls are still possible and done by value if the flag is set to True? Is there any negative effect when setting it to True?</p>