public function create_item_permissions_check( $request ) {
		$retval = true;

		if ( ! is_user_logged_in() ) {
			$retval = new WP_Error(
				'bp_rest_authorization_required',
				__( 'Sorry, you need to be logged in to join a group.', 'buddypress' ),
				array(
					'status' => rest_authorization_required_code(),
				)
			);
		}

		$user = bp_rest_get_user( $request['user_id'] );

		if ( true === $retval && ! $user instanceof WP_User ) {
			$retval = new WP_Error(
				'bp_rest_group_member_invalid_id',
				__( 'Invalid group member ID.', 'buddypress' ),
				array(
					'status' => 404,
				)
			);
		}

		$group = $this->groups_endpoint->get_group_object( $request['group_id'] );
		if ( true === $retval && ! $group instanceof BP_Groups_Group ) {
			$retval = new WP_Error(
				'bp_rest_group_invalid_id',
				__( 'Invalid group ID.', 'buddypress' ),
				array(
					'status' => 404,
				)
			);
		}

		// Site administrators can do anything.
		if ( true === $retval && bp_current_user_can( 'bp_moderate' ) ) {
			$retval = true;
		} else {

			$loggedin_user_id = bp_loggedin_user_id();
			if ( $loggedin_user_id === $user->ID && 'view' === $request['context'] ) {

				// Users may only freely join public groups.
				if ( true === $retval && (
					! bp_current_user_can( 'groups_join_group', array( 'group_id' => $group->id ) )
					|| groups_is_user_member( $loggedin_user_id, $group->id ) // As soon as they are not already members.
					|| groups_is_user_banned( $loggedin_user_id, $group->id ) // And as soon as they are not banned from it.
				) ) {
					$retval = new WP_Error(
						'bp_rest_group_member_failed_to_join',
						__( 'Could not join the group.', 'buddypress' ),
						array(
							'status' => 500,
						)
					);
				}

				if ( true === $retval ) {
					$retval = true;
				}
			} else {
				$retval = false;
			}
		}

		/**
		 * Filter the group members `create_item` permissions check.
		 *
		 * @since 5.0.0
		 *
		 * @param bool|WP_Error   $retval  Returned value.
		 * @param WP_REST_Request $request The request sent to the API.
		 */
		return apply_filters( 'bp_rest_group_members_create_item_permissions_check', $retval, $request );
	}