JVM doesn't stop after running WsdlTestStep

Hi all. When I execute this "tricky" example as a java main I get a correct execution without any exception. The problem is that the Java Virtual Machine doesn´t stop all Threads and remains running.
I don't know if I need to set some properties.

Thanks in advance.

WsdlProject project  = new WsdlProject(PROJECT_PATH, BLANK);
WsdlTestSuite testSuite = project.getTestSuiteByName(testSuiteName);
WsdlTestCase testCase  = testSuite.getTestCaseByName(testCaseName);
WsdlTestStep testStep  = testCase.getTestStepByName(testStepName);

WsdlTestRunContext testStepContext = new WsdlTestRunContext(testStep);
WsdlTestCaseRunner testCaseRunner = new WsdlTestCaseRunner(testCase, testStepContext.getProperties());
testCaseRunner.runTestStep(testStep);

if (testCaseRunner.isFailed())
  System.out.println("testStep FAILED");
else
  System.out.println("testStep OK");