few targeted uses of "!isset()" in place of "null ==="

Author: dcarbone

src/Catalog/GatewayService.php

@@ -90,10 +90,10 @@ class GatewayService extends AbstractModel
     public function __construct(?array $data = [])
     {
         parent::__construct($data);
-        if (null === $this->Gateway) {
+        if (!isset($this->Gateway)) {
             $this->Gateway = new CompoundServiceName();
         }
-        if (null === $this->Service) {
+        if (!isset($this->Service)) {
             $this->Service = new CompoundServiceName();
         }
     }

src/RequestResponse.php

@@ -98,7 +98,7 @@ public function buildQueryMeta(): QueryMeta
 
         // if there was no response, return as-is
         // note: should never see this in the wild.
-        if (null === $this->Response) {
+        if (!isset($this->Response)) {
             return $qm;
         }
 

tests/Usage/KV/KVClientCASTest.php

@@ -16,6 +16,7 @@ final class KVClientCASTest extends AbstractUsageTests
     public const KVOriginalValue = 'originalvalue';
     public const KVUpdatedValue  = 'updatedvalue';
     public const KVUpdatedValue2 = 'updatedvalue2';
+
     /** @var bool */
     protected static $singlePerClass = true;