src/properties/class-papi-property-relationship.php
public function sort_value( $values, $slug, $post_id ) {
		$sort_option  = $this->get_sort_option( $post_id );
		$sort_options = static::get_sort_options();

		if ( empty( $sort_option ) || ! isset( $sort_options[$sort_option] ) || is_null( $sort_options[$sort_option] ) ) {
			return $values;
		}

		usort( $values, $sort_options[$sort_option] );

		return $values;
	}
public function sort_value( $values, $slug, $post_id ) {
		$sort_option  = $this->get_sort_option( $post_id );
		$sort_options = static::get_sort_options();

		if ( empty( $sort_option ) || ! isset( $sort_options[$sort_option] ) || is_null( $sort_options[$sort_option] ) ) {
			return $values;
		}

		usort( $values, $sort_options[$sort_option] );

		return $values;
	}
Sort the values.

@param  array  $values
@param  string $slug
@param  int    $post_id

@return array