simplify getLanguage call in request

Message/RequestAbstract.php

@@ -232,6 +232,18 @@ abstract class RequestAbstract implements MessageInterface
         return $this->header;
     }
 
+    /**
+     * Get request language.
+     *
+     * @return string
+     *
+     * @since 1.0.0
+     */
+    public function getLanguage() : string
+    {
+        return $this->header->getL11n()->getLanguage();
+    }
+
     /**
      * Get request hash.
      *

Message/ResponseAbstract.php

@@ -103,6 +103,18 @@ abstract class ResponseAbstract implements \JsonSerializable, MessageInterface
         return $this->header;
     }
 
+    /**
+     * Get response language.
+     *
+     * @return string
+     *
+     * @since 1.0.0
+     */
+    public function getLanguage() : string
+    {
+        return $this->header->getL11n()->getLanguage();
+    }
+
     /**
      * Get response body.
      *

tests/Message/Console/ConsoleRequestTest.php

@@ -39,7 +39,7 @@ class ConsoleRequestTest extends \PHPUnit\Framework\TestCase
     public function testDefault() : void
     {
         $request = new ConsoleRequest();
-        self::assertEquals('en', $request->getHeader()->getL11n()->getLanguage());
+        self::assertEquals('en', $request->getLanguage());
         self::assertEquals(OSType::LINUX, $request->getOS());
         self::assertEquals('127.0.0.1', $request->getOrigin());
         self::assertEmpty($request->getBody());

tests/Message/Http/HttpRequestTest.php

@@ -42,7 +42,7 @@ class HttpRequestTest extends \PHPUnit\Framework\TestCase
 
         $_SERVER['HTTP_USER_AGENT'] = OSType::UNKNOWN . BrowserType::UNKNOWN;
 
-        self::assertEquals('en', $request->getHeader()->getL11n()->getLanguage());
+        self::assertEquals('en', $request->getLanguage());
         self::assertFalse($request->isMobile());
         self::assertEquals(BrowserType::UNKNOWN, $request->getBrowser());
         self::assertEquals(OSType::UNKNOWN, $request->getOS());