#### Bug, feature request, or proposal: md-Checkbox should pass "required" to the inner checkbox #### What is the expected behavior? When marking a md-checkbox with required, the underlying input-element should have a "required" attribute. #### What is the current behavior? the required attribute is not passed to the underlying input-element when using md-checkbox but when using md-input it works #### What are the steps to reproduce? http://plnkr.co/edit/DbPdlyZrfgv3iZsQUNS4?p=preview #### What is the use-case or motivation for changing an existing behavior? The HTML5-Validation of required checkboxes should work, this is especially important when working with indeterminate checkboxes #### Which versions of Angular, Material, OS, browsers are affected? looks like everyone #### Is there anything else we should know?