public static void notNull(Object object) {
        notNull(object, "[Assertion failed] - this argument is required; it must not be null");
    }
Assert that an object is not {@code null} .
<pre class="code">Assert.notNull(clazz);</pre>

@param object the object to check
@throws IllegalArgumentException if the object is {@code null}
src/main/java/spark/utils/Assert.java