The assertion datatype. This type describes
 assertion settings for the <java> task and others.
 One can set the system assertions, and enable/disable those in
 packages and classes.
 Assertions can only be enabled or disabled when forking Java.
 Example: set system assertions and all org.apache packages except
 for ant, and the class org.apache.tools.ant.Main.
 
 <assertions enableSystemAssertions="true" >
   <enable package="org.apache" />
   <disable package="org.apache.ant" />
   <enable class="org.apache.tools.ant.Main"/>
 </assertions>
 Disable system assertions; enable those in the anonymous package
 
 <assertions enableSystemAssertions="false" >
   <enable package="..." />
 </assertions>
 
 enable assertions in a class called Test
 
 <assertions >
   <enable class="Test" />
 </assertions>
 
 This type is a datatype, so you can declare assertions and use them later
 
 <assertions id="project.assertions" >
   <enable project="org.apache.test" />
 </assertions>
 <assertions refid="project.assertions" />