public  void addFileset(FileSet set) 
{
        fileSets.add( set );
}

Adds a set of files (nested fileset attribute).

 public  void execute() 
{
        log( "PDFToTextTask executing" );
        Iterator fileSetIter = fileSets.iterator();
        while( fileSetIter.hasNext() )
        {
            FileSet next = (FileSet)fileSetIter.next();
            DirectoryScanner dirScanner = next.getDirectoryScanner( getProject() );
            dirScanner.scan();
            String[] files = dirScanner.getIncludedFiles();
            for( int i=0; i< files.length; i++ )
            {
                File f = new File( dirScanner.getBasedir(), files[i] );
                log( "processing: " + f.getAbsolutePath() );
                String pdfFile = f.getAbsolutePath();
                if( pdfFile.toUpperCase().endsWith( ".PDF" ) )
                {
                    String textFile = pdfFile.substring( 0, pdfFile.length() -3 );
                    textFile = textFile + "txt";
                    try
                    {
                        org.apache.pdfbox.ExtractText.main( new String[] { pdfFile, textFile } );
                    }
                    catch( Exception e )
                    {
                        log( "Error processing " + pdfFile + e.getMessage() );
                    }
                }
            }
        }
}

This will perform the execution.