bp_document_media_library_list_view_document_attachment_image( array $attr, WP_Post $attachment, string $size )

function bp_document_media_library_list_view_document_attachment_image( $attr, $attachment, $size ) {
	if ( ! is_admin() ) {
		return $attr;
	}

	global $current_screen;

	if (
		empty( $current_screen )
		|| ! isset( $current_screen->parent_file )
		|| $current_screen->parent_file !== 'upload.php'
		|| empty( $attachment )
		|| empty( $attachment->ID )
	) {
		return $attr;
	}

	$meta = get_post_meta( $attachment->ID, '_wp_attached_file', true );
	if ( empty( $meta ) ) {
		return $attr;
	}

	if ( strstr( $meta, 'bb_documents/' ) ) {
		$attr['src']   = includes_url() . 'images/media/default.png';
		$attr['style'] = "width:42px;height:60px;border:0;";
	}

	return $attr;
}