private File processingSingleDirectory(File dir) throws IOException, InterruptedException {
		if (dir.exists() == false) {
			final String s = "The file " + dir.getAbsolutePath() + " does not exists.";
			this.log(s);
			throw new BuildException(s);
		}
		for (File f : dir.listFiles()) {
			if (f.isFile() == false) {
				continue;
			}
			if (fileToProcess(f.getName()) == false) {
				continue;
			}
			final boolean error = processingSingleFile(f);
			if (error) {
				return f;
			}
		}
		return null;
	}