function _expandableChanged(bExpandable){

		if (bExpandable) {
			if (!this._oExpandButton) {
				if (this._oInitPromise) {
					// module needs to be loaded -> create Button async
					this._oInitPromise.then(function () {
						delete this._oInitPromise; // not longer needed as resolved
						_expandButtonCreated.call(this, FormHelper.createButton(this.getId() + "--Exp", _handleExpButtonPress, this));
					}.bind(this));
				} else {
					_expandButtonCreated.call(this, FormHelper.createButton(this.getId() + "--Exp", _handleExpButtonPress, this));
				}
			} else {
				_setExpanderIcon.call(this);
			}
		}

	}
Association to controls / IDs that label this control (see WAI-ARIA attribute <code>aria-labelledby</code>).

<b>Note:</b> This attribute is only rendered if the <code>FormContainer</code> has it's own
DOM representation in the used <code>FormLayout</code>.

<b>Note:</b> If there is more than one <code>FormContainers</code>, every <code>FormContainer</code> needs to have some title or label
(at least for screen reader support).
If no <code>Title</code> is set, a label or title needs to be assigned using the <code>ariaLabelledBy</code> association.
@since 1.36.0