private Set collectFilesToProcess() {
DirectoryScanner scanner = new DirectoryScanner();
scanner.setBasedir( instrumentationDirectory );
scanner.setIncludes( new String[] { "**/*.class" } );
scanner.addDefaultExcludes();
scanner.scan();
String[] includedFiles = scanner.getIncludedFiles();
HashSet fileSet = new HashSet( includedFiles.length + (int)(.75*includedFiles.length) + 1 );
fileSet.addAll( Arrays.asList( includedFiles ) );
return fileSet;