alfresco-ng2-components/lib/process-services/src/lib/attachment/create-task-attachment.component.html

<button
    color="primary"
    mat-button
    class="adf-create-attachment"
    [adf-upload]="true"
    [mode]="['click']"
    [multiple]="true"
    (upload-files)="onFileUpload($event)">
    <mat-icon>add</mat-icon>
</button>