message: Work for Add docs for buttongroup item properties
diff: @@ -2,6 +2,7 @@ import { Serializer, property } from "./jsonobject";
  import { QuestionFactory } from "./questionfactory";
  import { ItemValue } from "./itemvalue";
  import { QuestionCheckboxBase } from "./question_baseselect";
  +import { LocalizableString } from "./localizablestring";
  export class ButtonGroupItemValue extends ItemValue {
  constructor(
  @@ -11,10 +12,21 @@ export class ButtonGroupItemValue extends ItemValue {
  ) {
  super(value, text, typeName);
  }
  + /*
  + Item icon property
  + */
  @property()
  iconName: string;
  + /*
  + By default icon size is 24.
  + Use this property to change item icon size.
  + */
  @property()
  iconSize: number;
  + /**
  + * By default item caption is visible.
  + * Set it 'false' to hide item caption.
  + */
  @property()
  showCaption: boolean;
  public getType(): string {
  @@ -85,7 +97,7 @@ export class ButtonGroupItemModel {
  public get iconSize() {
  return this.item.iconSize || 24;
  }
  - public get caption() {
  + public get caption(): LocalizableString {
  return this.item.locText;
  }
  public get showCaption() {
  