stay-open-on-select is not taken into account

The following elements should take into account stay-open-on-select parameter (according to ELEMENTS-365):

1. nuxeo-directory-suggestion
2. nuxeo-document-suggestion
3. nuxeo-select2
4. nuxeo-tag-suggestion
5. nuxeo-user-suggestion

But the following does not keep the dropdown box open after clicking:

    <nuxeo-user-suggestion role="widget" value="{{document.properties.mydoc:myUser}}" label="My User" multiple="true" search-type="USER_GROUP_TYPE" stay-open-on-select="true" ></nuxeo-user-suggestion>

Steps to reproduce:

1. install Nuxeo 8.10
2. add a multi-valued user-typed property
3. customize the form in web designer as above (add the stay-open-on-select="true" part)
4. in the UI click the create form
5. select one user
6. observe the box is closed right after the click

Expected behavior: the box should remain open

Please note the user elements has been used but this is a common issue for all the elements listed above.