title: ESAPI throwing org.owasp.esapi.errors.ConfigurationException when trying to log a warning
body: <p>We've added a filter to our spring webapp that checks all incoming requests for anything that could cause an XSS vulnerability. However, when it tries to write to the log, we get the following stack trace:</p>
  
  <pre><code>com.blah.blah.web.controllers.ExceptionLoggingController - ERROR: Exception: code=500,uri=/post.html,servlet=dispatch,class=org.owasp.esapi.errors.ConfigurationException,from=1.2.3.4,message=Request processing failed; nested exception is org.owasp.esapi.errors.ConfigurationException: java.lang.IllegalArgumentException: Classname cannot be null or empty. HTTPUtilities type name cannot be null or empty.
  org.owasp.esapi.errors.ConfigurationException: java.lang.IllegalArgumentException: Classname cannot be null or empty. HTTPUtilities type name cannot be null or empty.
      at org.owasp.esapi.util.ObjFactory.make(ObjFactory.java:105)
      at org.owasp.esapi.ESAPI.httpUtilities(ESAPI.java:121)
      at org.owasp.esapi.ESAPI.currentRequest(ESAPI.java:70)
      at org.owasp.esapi.reference.JavaLogFactory$JavaLogger.log(JavaLogFactory.java:308)
      at org.owasp.esapi.reference.JavaLogFactory$JavaLogger.warning(JavaLogFactory.java:242)
      at org.owasp.esapi.reference.DefaultEncoder.canonicalize(DefaultEncoder.java:181)
      at org.owasp.esapi.reference.DefaultEncoder.canonicalize(DefaultEncoder.java:120)
      at com.blah.blah.web.MyFilter.removeXSS(MyFilter.java:26)
  </code></pre>
  
  <p>I have ESAPI.properties on the classpath, that seems to be otherwise working, that does have the "missing" class configured:</p>
  
  <pre><code>ESAPI.HTTPUtilities=org.owasp.esapi.reference.DefaultHTTPUtilities
  </code></pre>
  
  <p>And DefaultHTTPUtilities is on the classpath as well.</p>