Smart search generates bad NXQL expression when using a 'vocabulary' widget with entry ID contains comma

When a Single vocabulary (or a Single directory suggestion) is used to select a value for a field in a smart search and when the vocabulary entry's ID contains a comma, a list of values is generated instead of a simple string value containing a comma.

How to reproduce:

• create a new vocabulary named ContentSpot:
• add an entry with id set to 1,2 and label set to 1,2
• create a new document type named Digital_File:
• change its schema's prefix to dg
• add a String field named ContentSpotDesc to it
• under the creation layout, add a Single vocabulary widget for field dg:ContentSpotDesc with vocabulary ContentSpot
• create a new XML extension with the following XML:

  <require>org.nuxeo.ecm.platform.smart.query.layouts</require>
  
  <extension target="org.nuxeo.ecm.platform.forms.layout.WebLayoutManager" point="widgets">
  
    <widget name="nxql_smart_query_condition_contentspot_Splty"
      type="incremental_smart_query_condition">
      <labels>
        <label mode="any">Specialty Content Spot</label>
      </labels>
      <translated>true</translated>
      <properties widgetMode="edit">
        <property name="searchField">dg:ContentSpotDesc</property>
        <propertyList name="availableOperators">
          <value>IN</value>
        </propertyList>
      </properties>
      <subWidgets>
        <widget name="Splty_contentspot_select_multi"
          type="suggestManyDirectory">
          <fields>
            <field>stringListValue</field>
          </fields>
          <widgetModes>
            <!-- to show only when using 'IN' or 'NOT IN' -->
            <mode value="any">
  
              #{not empty value.conditionalOperator
              and
              value.conditionalOperator!='IN'
              and
              value.conditionalOperator!='NOT
              IN'?'hidden':mode}
  
            </mode>
          </widgetModes>
          <properties mode="any">
            <property name="width">100%</property>
            <property name="dbl10n">true</property>
            <property name="minChars">0</property>
            <property name="hideHelpLabel">true</property>
            <property name="directoryName">ContentSpot</property>
          </properties>
        </widget>
        <widget name="splty_content_spot_text" type="text">
          <fields>
            <field>stringValue</field>
          </fields>
          <widgetModes>
            <!-- use in other cases -->
            <mode value="any">
  
              #{empty value.conditionalOperator
              or
              value.conditionalOperator=='IN'
              or
              value.conditionalOperator=='NOT
              IN'
              or value.conditionalOperator=='='
              or
              value.conditionalOperator=='!='?'hidden':mode}
            </mode>
          </widgetModes>
        </widget>
      </subWidgets>
    </widget>
  
  </extension>
  
    <extension target="org.nuxeo.ecm.platform.forms.layout.WebLayoutManager" point="layouts">
  
      <layout name="incremental_smart_query_selection">
        <templates>
          <template mode="any">
            /layouts/incremental_smart_query_selection_layout_template.xhtml
          </template>
        </templates>
        <properties mode="any">
          <property name="hideNotOperator">true</property>
        </properties>
        <rows>
          <row name="nxql_smart_query_condition_fulltext">
            <widget>nxql_smart_query_condition_fulltext</widget>
          </row>
          <row name="nxql_smart_query_condition_title">
            <widget>nxql_smart_query_condition_title</widget>
          </row>
          <row name="nxql_smart_query_condition_contentspot_Splty">
            <widget>nxql_smart_query_condition_contentspot_Splty</widget>
          </row>
          <row name="nxql_smart_query_condition_created">
            <widget>nxql_smart_query_condition_created</widget>
          </row>
          <row name="nxql_smart_query_condition_contributors">
            <widget>nxql_smart_query_condition_contributors</widget>
          </row>
          <row name="nxql_smart_query_condition_modified">
            <widget>nxql_smart_query_condition_modified</widget>
          </row>
          <row name="nxql_smart_query_condition_expired">
            <widget>nxql_smart_query_condition_expired</widget>
          </row>
          <row name="nxql_smart_query_condition_nature">
            <widget>nxql_smart_query_condition_nature</widget>
          </row>
          <row name="nxql_smart_query_condition_subjects">
            <widget>nxql_smart_query_condition_subjects</widget>
          </row>
          <row name="nxql_smart_query_condition_coverage">
            <widget>nxql_smart_query_condition_coverage</widget>
          </row>
          <row name="nxql_smart_query_condition_description">
            <widget>nxql_smart_query_condition_description</widget>
          </row>
          <row name="nxql_smart_query_condition_rights">
            <widget>nxql_smart_query_condition_rights</widget>
          </row>
          <row name="nxql_smart_query_condition_source">
            <widget>nxql_smart_query_condition_source</widget>
          </row>
          <row name="nxql_smart_query_condition_format">
            <widget>nxql_smart_query_condition_format</widget>
          </row>
          <row name="nxql_smart_query_condition_language">
            <widget>nxql_smart_query_condition_language</widget>
          </row>
          <row name="nxql_smart_query_condition_path">
            <widget>nxql_smart_query_condition_path</widget>
          </row>
        </rows>
      </layout>
  
  </extension>
  

• deploy
• log in and create a new document of type Digital_File in a workspace:
• select the only vocabulary entry 1,2 for field ContentSpotDesc
• save document
• navigate to main tab SEARCH and select Smart Search in top-left drop down
• select field Specialty Content Spot in field selection drop down
• select the only vocabulary entry 1,2 for its value
• click Add button

Expected result: dg:ContentSpotDesc IN ('1,2') is inserted in text area
Actual result: dg:ContentSpotDesc IN ('1','2') is inserted in text area