Wrong plugin call in frontend using ButtonDropdown widget

[yii-bot]

This issue has originally been reported by @yukal at yiisoft/yii2#13798.
Moved here by @samdark.

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I trying to call ButtonDropdown::widget by example of official documentation of Yii2
And everything looks fine, but when I clicking to the button it's not collapsing. Then I opened rendered html code and find this strings below:
$('#btn-dropdown').button()

And then I look into Bootstrap documentation, and found out that I need to use dropdown instead of button...
$('#btn-dropdown').dropdown()

So

• Why ButtonDropdown widget call $().button() in end of file, when we expected $().dropdown()?
• And how can I call .dropdown() instead .button()?

Additional info

Q	A
Yii version	2.0.7 (advanced)
PHP version	5.5.38
Operating system	Centos 7