@Test
  public void testGetClauseFromParamsFilteredValuesEmpty() throws Exception {
    final CustomFieldParams customFieldParams = mockController.getMock(CustomFieldParams.class);
    customFieldParams.getAllValues();
    mockController.setReturnValue(CollectionBuilder.newBuilder("").asMutableSet());

    final VersionCustomFieldSearchInputTransformer inputTransformer =
        createTransformer("cf[12345]");

    assertNull(inputTransformer.getClauseFromParams(theUser, customFieldParams, null));

    mockController.verify();
  }
  @Override
  public void validateFromParams(
      CustomFieldParams cfParams, ErrorCollection errorCollection, FieldConfig fieldConfig) {
    @SuppressWarnings("unchecked")
    final Collection<String> params = cfParams.getAllValues();
    CustomField cf = fieldConfig.getCustomField();
    JiraAuthenticationContext authCtx =
        ComponentManager.getInstance().getJiraAuthenticationContext();
    I18nHelper i18n = authCtx.getI18nHelper();
    UserProjectHistoryManager userProjectHistoryManager =
        ComponentManager.getComponentInstanceOfType(UserProjectHistoryManager.class);
    Project currentProject =
        userProjectHistoryManager.getCurrentProject(Permissions.BROWSE, authCtx.getLoggedInUser());

    boolean isAutocompleteView;
    if (cf.isAllProjects()) {
      isAutocompleteView =
          qfMgr.isAutocompleteView(cf.getIdAsLong(), Consts.PROJECT_ID_FOR_GLOBAL_CF);
    } else {
      isAutocompleteView = qfMgr.isAutocompleteView(cf.getIdAsLong(), currentProject.getId());
    }

    if (isAutocompleteView) {
      if ((params == null) || params.isEmpty()) {
        boolean addNull;
        if (cf.isAllProjects()) {
          addNull = qfMgr.getAddNull(cf.getIdAsLong(), Consts.PROJECT_ID_FOR_GLOBAL_CF);
        } else {
          addNull = qfMgr.getAddNull(cf.getIdAsLong(), currentProject.getId());
        }

        if (!addNull) {
          errorCollection.addError(
              fieldConfig.getFieldId(), i18n.getText("queryfields.error.isnotnull"));
        }
      } else {
        if (params.size() > 1) {
          errorCollection.addError(
              fieldConfig.getFieldId(), i18n.getText("queryfields.error.invalid.params"));
        } else {
          for (String param : params) {
            Issue issue = issueMgr.getIssueObject(param);
            if (issue == null) {
              errorCollection.addError(
                  fieldConfig.getFieldId(), i18n.getText("queryfields.error.notissue", param));
            }
          }
        }
      }
    }
  }