added "SUBJECT" to paypal request (allows executing api calls on behalf of a third-party)

added test for new value

Author: Vladislav Veselinov

src/Omnipay/PayPal/Message/AbstractRequest.php

@@ -49,6 +49,16 @@ public function setSignature($value)
         return $this->setParameter('signature', $value);
     }
 
+    public function getSubject()
+    {
+        return $this->getParameter('subject');
+    }
+
+    public function setSubject($value)
+    {
+        return $this->setParameter('subject', $value);
+    }
+
     public function getSolutionType()
     {
         return $this->getParameter('solutionType');
@@ -87,6 +97,7 @@ protected function getBaseData($method)
         $data['USER'] = $this->getUsername();
         $data['PWD'] = $this->getPassword();
         $data['SIGNATURE'] = $this->getSignature();
+        $data['SUBJECT'] = $this->getSubject();
 
         return $data;
     }

tests/Omnipay/PayPal/Message/ExpressAuthorizeRequestTest.php

@@ -39,6 +39,7 @@ public function testGetData()
             'returnUrl' => 'https://www.example.com/return',
             'cancelUrl' => 'https://www.example.com/cancel',
             'notifyUrl' => 'https://www.example.com/notify',
+            'subject' => '[email protected]',
             'headerImageUrl' => 'https://www.example.com/header.jpg',
         ));
 
@@ -51,6 +52,7 @@ public function testGetData()
         $this->assertSame('https://www.example.com/return', $data['RETURNURL']);
         $this->assertSame('https://www.example.com/cancel', $data['CANCELURL']);
         $this->assertSame('https://www.example.com/notify', $data['PAYMENTREQUEST_0_NOTIFYURL']);
+        $this->assertSame('[email protected]', $data['SUBJECT']);
         $this->assertSame('https://www.example.com/header.jpg', $data['HDRIMG']);
     }