Source

File: wp-includes/class-wp-roles.php

public function init_roles() {
		if ( empty( $this->roles ) ) {
			return;
		}

		$this->role_objects = array();
		$this->role_names   = array();
		foreach ( array_keys( $this->roles ) as $role ) {
			$this->role_objects[ $role ] = new WP_Role( $role, $this->roles[ $role ]['capabilities'] );
			$this->role_names[ $role ]   = $this->roles[ $role ]['name'];
		}

		/**
		 * After the roles have been initialized, allow plugins to add their own roles.
		 *
		 * @since 4.7.0
		 *
		 * @param WP_Roles $this A reference to the WP_Roles object.
		 */
		do_action( 'wp_roles_init', $this );
	}