Builds the overview form for the source entities.
array $form: Drupal form array.
\Drupal\Core\Form\FormStateInterface $form_state: The current state of the form.
string $type: Entity type.
array Drupal form array.
public function overviewForm(array $form, FormStateInterface $form_state, $type) {
$form += $this
->overviewSearchFormPart($form, $form_state, $type);
$form['#attached']['library'][] = 'tmgmt/admin';
$form['items'] = array(
'#type' => 'tableselect',
'#header' => $this
->overviewFormHeader($type),
'#empty' => $this
->t('No source items matching given criteria have been found.'),
);
return $form;
}