public static void notEmpty(Map map) {
        notEmpty(map, "[Assertion failed] - this map must not be empty; it must contain at least one entry");
    }
Assert that a Map has entries; that is, it must not be <code>null</code>
and must have at least one entry.
<pre class="code">Assert.notEmpty(map);</pre>
@param map the map to check
@throws IllegalArgumentException if the map is <code>null</code> or has no entries
src/main/java/org/apache/shiro/lang/util/Assert.java