public static void isNull(Object object) {
        isNull(object, "[Assertion failed] - the object argument must be null");
    }
Assert that an object is <code>null</code> .
<pre class="code">Assert.isNull(value);</pre>

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