message: Fix import of MatExpansionModule
diff: import {NgModule} from '@angular/core';
  import {
  MatAutocompleteModule,
  - MatExpansionModule,
  MatButtonModule,
  MatCardModule,
  MatCheckboxModule,
  MatDialogModule,
  + MatExpansionModule,
  MatFormFieldModule,
  MatIconModule,
  MatInputModule,
  @@ -16,13 +16,12 @@ import {
  MatProgressBarModule, MatRadioModule,
  MatSelectModule, MatSlideToggleModule,
  MatSnackBarModule, MatTabsModule,
  - MatToolbarModule, MatTooltipModule, MatExpansionModule,
  + MatToolbarModule, MatTooltipModule
  } from '@angular/material';
  @NgModule({
  imports: [
  MatAutocompleteModule,
  - MatExpansionModule,
  MatButtonModule,
  MatCardModule,
  MatCheckboxModule,
  @@ -46,7 +45,6 @@ import {
  ],
  exports: [
  MatAutocompleteModule,
  - MatExpansionModule,
  MatButtonModule,
  MatCardModule,
  MatCheckboxModule,
  