The DropdownToggle component leaks the color attribute with default value of "secondary" which isn't used by bootstrap for stylizing the DropdownToggle html native element. It appears it was a copy/paste issue from other components that has never been used. This results in invalid HTML5 warnings when validating source.

<div data-toggle="dropdown" aria-haspopup="true" color="secondary"

• version 4.6.2
• components: DropdownToggle