Environment:
JDeveloper 11.1.1.6.0 
logj42  (apache-log4j-2.0-beta2-bin)
Windows 7 64bits

Steps to Reproduce:
//config file presents or not - does not meter.

Run / Debug simple application:

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class test_log {
    public test_log() {
        super();
    }
    
    static Logger logger = LogManager.getLogger(test_log.class.getName());

    public static void main(String[] args) {
        test_log test_log = new test_log();
      
        logger.entry();

        logger.debug("test");

        logger.error("test Err");

        logger.exit();
    

    }
...
}

Actual Results:
Failed with error
java.lang.ExceptionInInitializerError
	at view.test_log.<clinit>(test_log.java:13)
Caused by: java.lang.ClassCastException: oracle.xml.parser.v2.DTD cannot be cast to org.w3c.dom.Element
	at java.util.XMLUtils.load(XMLUtils.java:61)
	at java.util.Properties.loadFromXML(Properties.java:852)
	at org.apache.logging.log4j.LogManager.<clinit>(LogManager.java:77)

Additional Info:
When xmlparserv2.jar is deleted - application run fine.
But - it have to be presents - when deleted, JDeveloper failed to start.