Testing upgrade of httplug and switch to PSR-18

Author: dragonmantank

composer.json

@@ -31,18 +31,18 @@
   },
   "require": {
     "php": ">=7.1",
-    "php-http/client-implementation": "^1.0",
+    "psr/http-client-implementation": "^1.0",
     "laminas/laminas-diactoros": "^1.8.4 || ^2.0",
     "lcobucci/jwt": "^3.2",
     "ocramius/package-versions": "^1.4",
     "psr/container": "^1.0"
   },
   "require-dev": {
     "phpunit/phpunit": "^7.4",
-    "php-http/mock-client": "^0.3.0",
+    "php-http/mock-client": "^1.4",
     "estahn/phpunit-json-assertions": "^3.0.0",
     "squizlabs/php_codesniffer": "^3.1",
-    "php-http/guzzle6-adapter": "^1.0",
+    "php-http/guzzle6-adapter": "^2.0",
     "phpstan/phpstan": "^0.12.11"
   },
   "autoload": {

src/Client.php

@@ -26,6 +26,7 @@
 use Nexmo\Client\Factory\FactoryInterface;
 use Nexmo\Client\Credentials\SignatureSecret;
 use Nexmo\Client\Credentials\CredentialsInterface;
+use Psr\Http\Client\ClientInterface;
 
 /**
  * Nexmo API Client, allows access to the API from PHP.
@@ -75,7 +76,7 @@ class Client
     /**
      * Create a new API client using the provided credentials.
      */
-    public function __construct(CredentialsInterface $credentials, $options = array(), HttpClient $client = null)
+    public function __construct(CredentialsInterface $credentials, $options = array(), ClientInterface $client = null)
     {
         if (is_null($client)) {
             $client = new \Http\Adapter\Guzzle6\Client();
@@ -170,7 +171,7 @@ public function getApiUrl()
      * @param HttpClient $client
      * @return $this
      */
-    public function setHttpClient(HttpClient $client)
+    public function setHttpClient(ClientInterface $client)
     {
         $this->client = $client;
         return $this;