{
    "name": "chartmogul/chartmogul-php",
    "description": "ChartMogul API PHP Client",
    "type": "library",
    "license": "MIT",
    "authors": [
        {
            "name": "ChartMogul Ltd.",
            "email": "support@chartmogul.com"
        },
        {
            "name": "Mahmudul Hassan",
            "email": "rezatxe@gmail.com"
        }
    ],
    "autoload": {
        "psr-4": {
            "ChartMogul\\": "src/"
        }
    },
    "require": {
        "php": ">=5.4",
        "php-http/client-implementation": "^1.0",
        "zendframework/zend-diactoros": "^1.3",
        "php-http/guzzle6-adapter": "^1.0",
        "doctrine/collections": "^1.3"
    },
    "require-dev": {
        "php-http/mock-client": "^0.3",
        "squizlabs/php_codesniffer": "^2.7",
        "phpdocumentor/phpdocumentor": "^2.9",
        "phpunit/phpunit": "4.*",
        "evert/phpdoc-md": "^0.2.0"
    }
}

{
    "name": "chartmogul/chartmogul-php",
    "description": "ChartMogul API PHP Client",
    "type": "library",
    "license": "MIT",
    "authors": [
        {
            "name": "ChartMogul Ltd.",
            "email": "support@chartmogul.com"
        },
        {
            "name": "Mahmudul Hassan",
            "email": "rezatxe@gmail.com"
        }
    ],
    "autoload": {
        "psr-4": {
            "ChartMogul\\": "src/"
        }
    },
    "require": {
        "php": ">=5.5",
        "php-http/client-implementation": "^1.0",
        "zendframework/zend-diactoros": "^1.3",
        "php-http/guzzle6-adapter": "^1.0",
        "doctrine/collections": "^1.3"
    },
    "require-dev": {
        "php-http/mock-client": "^0.3",
        "squizlabs/php_codesniffer": "^2.7",
        "phpdocumentor/phpdocumentor": "^2.9",
        "phpunit/phpunit": "4.*",
        "evert/phpdoc-md": "^0.2.0"
    }
}

Update Composer version to correct
Update Composer version to correct

PHP Chartmogul is not supporting PHP 5.4. It's working only with PHP 5.5 or upper versions.
1) Current version is using a new PHP 5.5 feature (like this https://github.com/chartmogul/chartmogul-php/blob/master/src/Enrichment/Customer.php#L123)
2) `php-http/client-implementation` library currently working with PHP 5.5 or upper. https://packagist.org/packages/php-http/guzzle6-adapter#v1.0.0