Quick search suggester 'documentLookupByTitle' does not work with a MongoDB repository

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.lang.BooleanUtils;
import org.nuxeo.ecm.core.api.ClientException;
import org.nuxeo.ecm.core.api.DocumentModel;
import org.nuxeo.ecm.platform.query.api.PageProvider;
import org.nuxeo.ecm.platform.query.api.PageProviderService;
import org.nuxeo.ecm.platform.query.nxql.CoreQueryDocumentPageProvider;
import org.nuxeo.ecm.platform.query.nxql.NXQLQueryBuilder;
import org.nuxeo.ecm.platform.suggestbox.service.DocumentSuggestion;
import org.nuxeo.ecm.platform.suggestbox.service.Suggester;
import org.nuxeo.ecm.platform.suggestbox.service.Suggestion;
import org.nuxeo.ecm.platform.suggestbox.service.SuggestionContext;
import org.nuxeo.ecm.platform.suggestbox.service.SuggestionException;
import org.nuxeo.ecm.platform.suggestbox.service.descriptors.SuggesterDescriptor;
import org.nuxeo.runtime.api.Framework;

public class DocumentParameterLookupSuggester implements Suggester {

    protected String providerName = "DEFAULT_DOCUMENT_SUGGESTION";

    protected SuggesterDescriptor descriptor;
    
    protected boolean appendWildcard = true;

    @Override
    public void initWithParameters(SuggesterDescriptor descriptor) {
        this.descriptor = descriptor;
        String providerName = descriptor.getParameters().get("providerName");
        if (providerName != null) {
            this.providerName = providerName;
        }
        String appendWildcard = descriptor.getParameters().get("appendWildcard");
        if (appendWildcard != null) {
            this.appendWildcard = BooleanUtils.toBoolean(appendWildcard);
        }
    }

    @Override
    public List<Suggestion> suggest(String userInput, SuggestionContext context) throws SuggestionException {
        PageProviderService ppService = Framework.getLocalService(PageProviderService.class);
        if (ppService == null) {
            throw new SuggestionException("PageProviderService is not active");
        }
        Map<String, Serializable> props = new HashMap<String, Serializable>();
        props.put(CoreQueryDocumentPageProvider.CORE_SESSION_PROPERTY,
                (Serializable) context.session);
        userInput = NXQLQueryBuilder.sanitizeFulltextInput(userInput);
        if (userInput.trim().isEmpty()) {
            return Collections.emptyList();
        }
        if (!userInput.endsWith(" ") && appendWildcard) {
            // perform a prefix search on the last typed word
            userInput += "*";
        }
        try {
            List<Suggestion> suggestions = new ArrayList<Suggestion>();
            PageProvider<DocumentModel> pp = (PageProvider<DocumentModel>) ppService.getPageProvider(
                    providerName, null, null, null, props,
                    new Object[] { userInput });
            for (DocumentModel doc : pp.getCurrentPage()) {
                suggestions.add(DocumentSuggestion.fromDocumentModel(doc));
            }
            return suggestions;
        } catch (ClientException e) {
            throw new SuggestionException(String.format(
                    "Suggester '%s' failed to perform query with input '%s'",
                    descriptor.getName(), userInput), e);
        }
    }

}

<require>org.nuxeo.ecm.platform.suggestbox.core.defaultSuggesters</require>

<extension target="org.nuxeo.ecm.platform.suggestbox.service.SuggestionService"
    point="suggesters">

    <suggester class="org.nuxeo.ecm.platform.suggestbox.service.suggesters.DocumentParameterLookupSuggester" name="customDocumentLookupByTitle">
      <parameters>
        <parameter name="providerName">DEFAULT_DOCUMENT_SUGGESTION</parameter>
        <parameter name="appendWildcard">false</parameter>
      </parameters>
    </suggester>

</extension>

<require>org.nuxeo.ecm.platform.suggestbox.core.defaultSuggesters</require>
<extension point="suggesterGroups" target="org.nuxeo.ecm.platform.suggestbox.service.SuggestionService">

    <suggesterGroup name="searchbox">
      <suggesters>
        <suggesterName remove="true">documentLookupByTitle</suggesterName>
        <suggesterName >customDocumentLookupByTitle</suggesterName>
        <suggesterName >searchByUsersAndGroups</suggesterName>
      </suggesters>
    </suggesterGroup>

  </extension>