The information of java.compiler can not be gotten by using getProperties().

According to the API document,
http://java.sun.com/j2se/1.5.0/docs/api/index.html
The key "java.compiler" is listed at description of "getProperties()".

However, we can not actually get the informaiton of the key.

CONFIRMATION:
 Please compile and execute the following test program.
 we can not see "java.compiler" inf.

---- Test Program ---->
import java.util.*;

class props extends Thread {
    public static void main( String arg[] ) throws Exception {
        Properties p = System.getProperties();
        Enumeration<Object> e = p.keys();
        for( ;e.hasMoreElements();) {
            String key = (String)e.nextElement();
            String value = (String)p.get(key);
            System.out.println(key+"="+value);
        }
    }
}
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