public void download() {
        confirmSelection("download", () -> {
            final ExpressionOperator expression = selectionToExpression(this.criteria, getSelection());
            validateExpression(expression, exp -> {
                final FindMetaCriteria criteria = expressionToNonPagedCriteria(exp);
                showSummary(
                        criteria,
                        DocumentPermission.VIEW,
                        "downloaded",
                        "download",
                        "Confirm Download",
                        false,
                        () -> download(criteria));
            });
        });
    }
@param onSetExpression Called after the expression has been successfully
                       validated and set on the criteria. Can be null.
stroom-core-client/src/main/java/stroom/data/client/presenter/AbstractMetaListPresenter.java