import { CollectionViewer, DataSource } from '@angular/cdk/collections';
import { HttpErrorResponse } from '@angular/common/http';
-import { MatSort } from '@angular/material';
+import { MatSort } from '@angular/material/sort';
import { Observable } from 'rxjs/Observable';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
import { merge } from 'rxjs';