Program: 84520
Project: 84520
Buggy source:
public ModelAndView enroll(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
  String returnPage=request.getParameter("String_Node_Str");
  if (returnPage == null) {
    throw new IllegalArgumentException("String_Node_Str");
  }
  String patientIdStr=request.getParameter("String_Node_Str");
  String programIdStr=request.getParameter("String_Node_Str");
  String enrollmentDateStr=request.getParameter("String_Node_Str");
  String completionDateStr=request.getParameter("String_Node_Str");
  log.debug("String_Node_Str" + patientIdStr + "String_Node_Str"+ programIdStr+ "String_Node_Str"+ enrollmentDateStr);
  ProgramWorkflowService pws=Context.getProgramWorkflowService();
  CustomDateEditor cde=new CustomDateEditor(Context.getDateFormat(),true,10);
  cde.setAsText(enrollmentDateStr);
  Date enrollmentDate=(Date)cde.getValue();
  cde.setAsText(completionDateStr);
  Date completionDate=(Date)cde.getValue();
  Patient patient=Context.getPatientService().getPatient(Integer.valueOf(patientIdStr));
  Program program=pws.getProgram(Integer.valueOf(programIdStr));
  if (!pws.getPatientPrograms(patient,program,null,enrollmentDate,completionDate,null,false).isEmpty())   request.getSession().setAttribute(WebConstants.OPENMRS_ERROR_ATTR,"String_Node_Str");
 else {
    PatientProgram pp=new PatientProgram();
    pp.setPatient(patient);
    pp.setProgram(program);
    pp.setDateEnrolled(enrollmentDate);
    pp.setDateCompleted(completionDate);
    Context.getProgramWorkflowService().savePatientProgram(pp);
  }
  return new ModelAndView(new RedirectView(returnPage));
}

Fixed version (ground truth):
public ModelAndView enroll(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
  String returnPage=request.getParameter("String_Node_Str");
  if (returnPage == null) {
    throw new IllegalArgumentException("String_Node_Str");
  }
  String patientIdStr=request.getParameter("String_Node_Str");
  String programIdStr=request.getParameter("String_Node_Str");
  String enrollmentDateStr=request.getParameter("String_Node_Str");
  String completionDateStr=request.getParameter("String_Node_Str");
  log.debug("String_Node_Str" + patientIdStr + "String_Node_Str"+ programIdStr+ "String_Node_Str"+ enrollmentDateStr);
  ProgramWorkflowService pws=Context.getProgramWorkflowService();
  CustomDateEditor cde=new CustomDateEditor(Context.getDateFormat(),true,10);
  cde.setAsText(enrollmentDateStr);
  Date enrollmentDate=(Date)cde.getValue();
  cde.setAsText(completionDateStr);
  Date completionDate=(Date)cde.getValue();
  Patient patient=Context.getPatientService().getPatient(Integer.valueOf(patientIdStr));
  Program program=pws.getProgram(Integer.valueOf(programIdStr));
  if (!pws.getPatientPrograms(patient,program,null,completionDate,enrollmentDate,null,false).isEmpty())   request.getSession().setAttribute(WebConstants.OPENMRS_ERROR_ATTR,"String_Node_Str");
 else {
    PatientProgram pp=new PatientProgram();
    pp.setPatient(patient);
    pp.setProgram(program);
    pp.setDateEnrolled(enrollmentDate);
    pp.setDateCompleted(completionDate);
    Context.getProgramWorkflowService().savePatientProgram(pp);
  }
  return new ModelAndView(new RedirectView(returnPage));
}