public static void isNull(Object object, String message) {
        if (object != null) {
            throw new IllegalArgumentException(message);
        }
    }
Assert that an object is <code>null</code> .
<pre class="code">Assert.isNull(value, "The value must be null");</pre>

@param object  the object to check
@param message the exception message to use if the assertion fails
@throws IllegalArgumentException if the object is not <code>null</code>
lang/src/main/java/org/apache/shiro/lang/util/Assert.java