fix: remove aria-required attribute from DOM when false

Author: hackingharold

projects/material/src/lib/mat-dropzone/mat-dropzone.component.ts

@@ -112,7 +112,6 @@ export class MatDropzone
   private _placeholder = '';
 
   @Input()
-  @HostBinding('attr.aria-required')
   get required(): boolean {
     const controlRequired = this.ngControl?.control?.hasValidator(Validators.required);
     return this._required || controlRequired || false;
@@ -140,6 +139,13 @@ export class MatDropzone
     return this.empty && this.required ? null : this.errorState;
   }
 
+  @HostBinding('attr.aria-required')
+  get ariaRequired() {
+    // Accessibility guidelines say that the attribute should be omitted when false,
+    // so we return null instead of false to remove it from the DOM.
+    return this.required || null;
+  }
+
   ngAfterContentInit() {
     super.ngAfterContentInit();