I updated my material angular project to include an expandable detail row in my table. I needed to upgrade to rsjx 6 for this. Now I get the following error. I'm totally new with angular, so unfortunately I don't have a clue how to resolve this.

```
Property 'merge' does not exist on type 'typeof Observable'.

```

Can anyone help to resolve this error?

**app.component.ts**

```js
  /** Connect function called by the table to retrieve one stream containing the data to render. */
  connect(): Observable<Track[]> {
    // Listen for any changes in the base data, sorting, filtering, or pagination
    const displayDataChanges = [
    this._exampleDatabase.dataChange,
    this._sort.sortChange,
    this._filterChange,
    this._paginator.page
    ];

    this._exampleDatabase.getAllTracks();

    return Observable.merge(...displayDataChanges).map(() => {
      // Filter data
      this.filteredData = this._exampleDatabase.data.slice().filter((track: Track) => {
        const searchStr = (track.id + track.title + track.artist + track.year + track.comment + track.path).toLowerCase();
        return searchStr.indexOf(this.filter.toLowerCase()) !== -1;
      });

      // Sort filtered data
      const sortedData = this.sortData(this.filteredData.slice());

      // Grab the page's slice of the filtered sorted data.
      const startIndex = this._paginator.pageIndex * this._paginator.pageSize;
      this.renderedData = sortedData.splice(startIndex, this._paginator.pageSize);
      return this.renderedData;
    });
  }
```