Add private Custom Post Types to SearchWP.

searchwp-customizations.php

<?php

// Add private Custom Post Types to SearchWP.
add_filter( 'searchwp\sources', function( $sources ) {
  // Create a Source from each private CPT e.g.
	$sources[] = new \SearchWP\Sources\Post( 'my_private_cpt_name_1' );
	$sources[] = new \SearchWP\Sources\Post( 'my_private_cpt_name_2' );
	$sources[] = new \SearchWP\Sources\Post( 'my_private_cpt_name_3' );

	return $sources;
} );