vaadin-combo-box in LitElement

Flow
1

Hello,

Where can i find an example of vaadin-combo-box webcomponent created in a LitElement render method ?
I try to implement with dynamic data provider and filter capability but I can’t find the right way.

Thanks

static get properties() { 
      return {
        ref_id : String,
        label : String,
        required : {
          type : Boolean,
          default : false
        },filter: {
          type: String,
          observer: '_filterChanged'
        },
        loading: Boolean,
        repos: {
          type: Array,
          value: function () {
            return [];
          }
        },
        repo: String
      };
    }
	
	render() {
      return html`
      <vaadin-combo-box 
        id="${this.ref_id}" 
        label="${this.label}" 
        ?required=${this.required}
        error-message="${this.error_message}"
        value="${this.repo}"
        filter="${this.filter}"
        loading="${this.loading}" 
        filtered-items="${this.repos}" 
        @change='${this._setValue}' 
      ></vaadin-combo-box>
          `;
    }
	
	firstUpdated(changedProperties) {
      this._combo = this.shadowRoot.getElementById(`${this.ref_id}`);
      //this._combo.dataProvider = this._search;
    }
	
	_filterChanged() {
      this.debounce('filter', this._search, 500);
    }

    _search() {
      //if (!this.filter) return;
      this.loading = true;
      console.log(this.filter);
      http.get(`${ServerBase}combo_1.json`)
      .then(data => {
        this.repos = data.items.map(repo => repo['code']
);
        console.log(this.repos);
        //this._combo.filteredItems = this.repos;
          this.loading = false;
      }).catch(() => this.loading = false);
    }