Hotfix: default value for headers is string not null

src/Header/AuthenticationInfo.php

@@ -31,14 +31,12 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static($value);
-
-        return $header;
+        return new static($value);
     }
 
     public function __construct($value = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -51,7 +49,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()

src/Header/Authorization.php

@@ -31,14 +31,12 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static($value);
-
-        return $header;
+        return new static($value);
     }
 
     public function __construct($value = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -51,7 +49,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()

src/Header/ContentDisposition.php

@@ -31,14 +31,12 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static($value);
-
-        return $header;
+        return new static($value);
     }
 
     public function __construct($value = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -51,7 +49,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()

src/Header/ContentEncoding.php

@@ -30,14 +30,12 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static($value);
-
-        return $header;
+        return new static($value);
     }
 
     public function __construct($value = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -50,7 +48,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()

src/Header/ContentLanguage.php

@@ -31,14 +31,12 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static($value);
-
-        return $header;
+        return new static($value);
     }
 
     public function __construct($value = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -51,7 +49,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()

src/Header/ContentLength.php

@@ -31,9 +31,7 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static($value);
-
-        return $header;
+        return new static($value);
     }
 
     public function __construct($value = null)
@@ -51,7 +49,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()

src/Header/ContentMD5.php

@@ -28,14 +28,12 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static($value);
-
-        return $header;
+        return new static($value);
     }
 
     public function __construct($value = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -48,7 +46,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()

src/Header/ContentRange.php

@@ -31,14 +31,12 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static($value);
-
-        return $header;
+        return new static($value);
     }
 
     public function __construct($value = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -51,7 +49,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()

src/Header/ContentTransferEncoding.php

@@ -31,14 +31,12 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static(strtolower($value));
-
-        return $header;
+        return new static(strtolower($value));
     }
 
     public function __construct($value = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -51,7 +49,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()

src/Header/ContentType.php

@@ -69,7 +69,7 @@ public static function fromString($headerLine)
 
     public function __construct($value = null, $mediaType = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -146,7 +146,7 @@ public function getFieldName()
     public function getFieldValue()
     {
         if (null !== $this->value) {
-            return $this->value;
+            return (string) $this->value;
         }
         return $this->assembleValue();
     }
@@ -172,7 +172,7 @@ public function setMediaType($mediaType)
      */
     public function getMediaType()
     {
-        return $this->mediaType;
+        return (string) $this->mediaType;
     }
 
     /**

src/Header/Etag.php

@@ -28,14 +28,12 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static($value);
-
-        return $header;
+        return new static($value);
     }
 
     public function __construct($value = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -48,7 +46,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()

src/Header/Expect.php

@@ -28,14 +28,12 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static($value);
-
-        return $header;
+        return new static($value);
     }
 
     public function __construct($value = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -48,7 +46,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()

src/Header/From.php

@@ -28,14 +28,12 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static($value);
-
-        return $header;
+        return new static($value);
     }
 
     public function __construct($value = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -48,7 +46,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()

src/Header/Host.php

@@ -28,14 +28,12 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static($value);
-
-        return $header;
+        return new static($value);
     }
 
     public function __construct($value = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -48,7 +46,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()

src/Header/IfMatch.php

@@ -28,14 +28,12 @@ public static function fromString($headerLine)
         }
 
         // @todo implementation details
-        $header = new static($value);
-
-        return $header;
+        return new static($value);
     }
 
     public function __construct($value = null)
     {
-        if ($value) {
+        if ($value !== null) {
             HeaderValue::assertValid($value);
             $this->value = $value;
         }
@@ -48,7 +46,7 @@ public function getFieldName()
 
     public function getFieldValue()
     {
-        return $this->value;
+        return (string) $this->value;
     }
 
     public function toString()