@AfterClass
	public static void deleteTempDir() throws IOException {
		if (sourceDir.exists()) {
			FileUtils.cleanDirectory(sourceDir);
			FileUtils.deleteDirectory(sourceDir);
		}
	}
@author David Turanski
@author Gunnar Hillert
@author Gary Russell
spring-xd-dirt/src/test/java/org/springframework/xd/dirt/stream/FileSourceModuleTests.java