<mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>
<mat-row *matRowDef="let element; columns: displayedColumns;"
[class.example-expanded-row]="expandedElement === element"
(click)="expandedElement = expandedElement === element ? null : element"></mat-row>
<tr mat-row *matRowDef="let row; columns: ['expandedDetail']" class="message-row"></tr>
<mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>
<mat-row *matRowDef="let element; columns: displayedColumns;"
[class.example-expanded-row]="expandedElement === element"
(click)="expandedElement = expandedElement === element ? null : element"></mat-row>
<tr mat-row *matRowDef="let row; columns: ['expandedDetail']" class="message-row"></tr>