Composer not installing a package

"staudenmeir/eloquent-json-relations" not installing on composer install.But downloading on composer update. Here is my composer.json

{ "name": "laravel/lumen", "description": "The Laravel Lumen Framework.", "keywords": ["framework", "laravel", "lumen"], "license": "MIT", "type": "project", "require": { "php": ">=7.1.3", "doctrine/dbal": "^2.9", "guzzlehttp/guzzle": "^6.3", "kreait/firebase-php": "^4.0", "laravel/lumen-framework": "5.7.*", "lcobucci/jwt": "^3.2", "league/flysystem-aws-s3-v3": "~1.0", "staudenmeir/eloquent-json-relations": "^1.1", "vlucas/phpdotenv": "~2.2" }, "require-dev": { "fzaninotto/faker": "~1.4", "phpunit/phpunit": "~7.0", "mockery/mockery": "~1.0" }, "autoload": { "classmap": [ "database/seeds", "database/factories" ], "psr-4": { "App\": "app/" } }, "autoload-dev": { "classmap": [ "tests/" ] }, "scripts": { "post-root-package-install": [ "@php -r \"file_exists('.env') || copy('.env.example', '.env');\"" ] }, "config": { "preferred-install": "dist", "sort-packages": true, "optimize-autoloader": true }, "minimum-stability": "dev", "prefer-stable": true }

via Chebli Mohamed