sS sourceCodeOfJDKClass(Class c) {
  ret sourceCodeOfJDKClass(c.getName());
}

sS sourceCodeOfJDKClass(S className) {
  File jdkLocation = new File(getSystemProperty("java.home"));
  if (eqic(jdkLocation.getName(), "jre")) // get our of jre subdir
    jdkLocation = parentFile(jdkLocation);
  File srcZip = new File(jdkLocation, "src.zip");
  if (!srcZip.exists()) null;
  S path = classNameToJavaFile(className);
  ret loadTextFileFromZip(srcZip, path);
}