Fail the build if any of JARs is empty

ant.spec

@@ -372,6 +372,9 @@ install -d -m 755 $RPM_BUILD_ROOT%{_mavenpomdir}
 
 for jar in build/lib/*.jar
 do
+  # Make sure that installed JARs are not empty
+  jar tf ${jar} | egrep -q *.class
+
   jarname=$(basename $jar .jar)
   pomname="JPP.%{name}-${jarname}.pom"
 
@@ -610,6 +613,7 @@ cp -pr build/javadocs/* $RPM_BUILD_ROOT%{_javadocdir}/%{name}
 - Remove dependencies on xerces-j2 and xml-commons-apis
 - Convert %%global build_javadoc to conditional
 - Remove bootstrap code
+- Fail the build if any of JARs is empty
 
 * Mon Jun 03 2013 Stanislav Ochotnicky <sochotnicky@redhat.com> - 0:1.9.1-2
 - Enable unit tests