ノート：Hadoop Configuration.java

  private Document parse(DocumentBuilder builder, URL url)
      throws IOException, SAXException {
    if (!quietmode) {
      LOG.debug("parsing URL " + url);
    }
    if (url == null) {
      return null;
    }
    return parse(builder, url.openStream(), url.toString());
  }

とあるので、
Configuration conf = new Configuration();
conf.setQuietMode(false);


 static{
    //print deprecation warning if hadoop-site.xml is found in classpath
    ClassLoader cL = Thread.currentThread().getContextClassLoader();
    if (cL == null) {
      cL = Configuration.class.getClassLoader();
    }
    if(cL.getResource("hadoop-site.xml")!=null) {
      LOG.warn("DEPRECATED: hadoop-site.xml found in the classpath. " +
          "Usage of hadoop-site.xml is deprecated. Instead use core-site.xml, "
          + "mapred-site.xml and hdfs-site.xml to override properties of " +
          "core-default.xml, mapred-default.xml and hdfs-default.xml " +
          "respectively");
    }
    addDefaultResource("core-default.xml");
    addDefaultResource("core-site.xml");
  }


とあるので、
ClassLoader cl = Thread.currentThread().getContextClassLoader();
System.out.println(Thread.currentThread().getName()+" core-site.xml path = "+cl.getResource("core-site.xml"));