import java.io.*;
import java.util.jar.*;

File attachedJarFile = new File( basedir, "jar-with-unusual.ext" );
System.out.println( "Checking for existence of " + attachedJarFile );
if ( !attachedJarFile.isFile() )
{
    throw new Exception( "missing " + attachedJarFile );
}

JarFile attachedJar = new JarFile( attachedJarFile );
System.out.println( "Checking for existence of " + attachedJarFile.getName() + "!/META-INF/TESTING.SF" );
if ( attachedJar.getEntry( "META-INF/TESTING.SF" ) == null )
{
    throw new Exception( "missing " + attachedJarFile.getName() + "!/META-INF/TESTING.SF" );
}
System.out.println( "Checking for existence of " + attachedJarFile.getName() + "!/META-INF/TESTING.DSA" );
if ( attachedJar.getEntry( "META-INF/TESTING.DSA" ) == null )
{
    throw new Exception( "missing " + attachedJarFile.getName() + "!/META-INF/TESTING.DSA" );
}
attachedJar.close();

return true;