Program: 37738
Project: 37738
Buggy source:
@Transactional(propagation=Propagation.REQUIRED,readOnly=false) public UserInfo createUser(final UserInfo userRequest){
  userValidator.validateCreateUser(userRequest);
  Set<RoleEntity> roleEntities=new HashSet<>();
  List<RoleEntity> roleEntityList=roleRepository.findAll();
  for (  Long roleId : userRequest.getRoleIds()) {
    RoleEntity roleEntity=roleEntityList.parallelStream().filter((entity) -> entity.getRoleId().equals(roleId)).findFirst().orElse(null);
    if (!ValidatorUtil.isNull(roleEntity)) {
      roleEntities.add(roleEntity);
    }
 else {
      throw new RequestValidationException(messageUtil.getAttributeNotFound("String_Node_Str"));
    }
  }
  UserEntity userEntity=UserConversionUtil.toUserEntity(userRequest,roleEntities);
  String password=ValidatorUtil.randomAlphaNumeric(16);
  userEntity.setPassword(StringUtil.encodeString(password));
  userEntity.setIs2FaEnabled(true);
  userEntity=userRepository.save(userEntity);
  if (userEntity.getUserId() != null) {
    Map<String,Object> map=new HashMap<String,Object>();
    map.put("String_Node_Str",userEntity.getName());
    map.put("String_Node_Str",userEntity.getUsername());
    map.put("String_Node_Str",password);
    mailService.send(userEntity.getEmail(),mailUtils.getSubjectAccountUsername(),TemplateService.Template.ACCOUNT_USERNAME,map);
    mailService.send(userEntity.getEmail(),mailUtils.getSubjectAccountPassword(),TemplateService.Template.ACCOUNT_PASSWORD,map);
  }
  return UserConversionUtil.toUserInfo(userEntity);
}

Fixed version (ground truth):
@Transactional(propagation=Propagation.REQUIRED,readOnly=false) public UserInfo createUser(final UserInfo userRequest){
  userValidator.validateCreateUser(userRequest);
  Set<RoleEntity> roleEntities=new HashSet<>();
  List<RoleEntity> roleEntityList=roleRepository.findAll();
  for (  Long roleId : userRequest.getRoleIds()) {
    RoleEntity roleEntity=roleEntityList.parallelStream().filter((entity) -> entity.getRoleId().equals(roleId)).findFirst().orElse(null);
    if (!ValidatorUtil.isNull(roleEntity)) {
      roleEntities.add(roleEntity);
    }
 else {
      throw new RequestValidationException(messageUtil.getAttributeNotFound("String_Node_Str"));
    }
  }
  UserEntity userEntity=UserConversionUtil.toUserEntity(userRequest,roleEntities);
  String password=ValidatorUtil.randomAlphaNumeric(16);
  userEntity.setPassword(StringUtil.encodeString(password));
  userEntity.setIs2FaEnabled(true);
  userEntity=userRepository.save(userEntity);
  LOGGER.info("String_Node_Str" + userEntity.getUsername() + "String_Node_Str");
  if (userEntity.getUserId() != null) {
    Map<String,Object> map=new HashMap<String,Object>();
    map.put("String_Node_Str",userEntity.getName());
    map.put("String_Node_Str",userEntity.getUsername());
    map.put("String_Node_Str",password);
    mailService.send(userEntity.getEmail(),mailUtils.getSubjectAccountUsername(),TemplateService.Template.ACCOUNT_USERNAME,map);
    mailService.send(userEntity.getEmail(),mailUtils.getSubjectAccountPassword(),TemplateService.Template.ACCOUNT_PASSWORD,map);
    LOGGER.info("String_Node_Str" + userEntity.getUsername() + "String_Node_Str");
  }
  return UserConversionUtil.toUserInfo(userEntity);
}