import java.io.*;

File jfxFolder = new File( basedir, "jfx-app/target/jfx" );
if( !jfxFolder.exists() ){
    throw new Exception( "there should be a jfx-folder!");
}

// custom bundler does nothing but sysouts, but the normal jfx-jar should be there ;)
File jfxAppFolder = new File( jfxFolder, "app" );
if( !jfxAppFolder.exists() ){
    throw new Exception( "there should be a jfx-app-folder!");
}