code: @Override
  	public ZooClass defineEmptyClass(String className) {
  		DBTracer.logCall(this, className);
      	checkValidity(true);
      	if (!checkJavaClassNameConformity(className)) {
      		throw new IllegalArgumentException("Not a valid class name: \"" + className + "\"");
      	}
  		return sm.declareSchema(className, null);
  	}
docs: This declares a new database class schema. This method creates an empty class
  with no attributes. It does not consider any existing Java classes of the same name.
  @param className Class name
  @return New schema object
  @see ZooSchema#defineEmptyClass(String)