[4.4] Add return types on internal|final|private methods (bis)

Author: nicolas-grekas

Header/Headers.php

@@ -64,7 +64,7 @@ public function getMaxLineLength(): int
      *
      * @return $this
      */
-    public function addMailboxListHeader(string $name, array $addresses)
+    public function addMailboxListHeader(string $name, array $addresses): self
     {
         return $this->add(new MailboxListHeader($name, Address::createArray($addresses)));
     }
@@ -74,7 +74,7 @@ public function addMailboxListHeader(string $name, array $addresses)
      *
      * @return $this
      */
-    public function addMailboxHeader(string $name, $address)
+    public function addMailboxHeader(string $name, $address): self
     {
         return $this->add(new MailboxHeader($name, Address::create($address)));
     }
@@ -84,7 +84,7 @@ public function addMailboxHeader(string $name, $address)
      *
      * @return $this
      */
-    public function addIdHeader(string $name, $ids)
+    public function addIdHeader(string $name, $ids): self
     {
         return $this->add(new IdentificationHeader($name, $ids));
     }
@@ -94,31 +94,31 @@ public function addIdHeader(string $name, $ids)
      *
      * @return $this
      */
-    public function addPathHeader(string $name, $path)
+    public function addPathHeader(string $name, $path): self
     {
         return $this->add(new PathHeader($name, $path instanceof Address ? $path : new Address($path)));
     }
 
     /**
      * @return $this
      */
-    public function addDateHeader(string $name, \DateTimeInterface $dateTime)
+    public function addDateHeader(string $name, \DateTimeInterface $dateTime): self
     {
         return $this->add(new DateHeader($name, $dateTime));
     }
 
     /**
      * @return $this
      */
-    public function addTextHeader(string $name, string $value)
+    public function addTextHeader(string $name, string $value): self
     {
         return $this->add(new UnstructuredHeader($name, $value));
     }
 
     /**
      * @return $this
      */
-    public function addParameterizedHeader(string $name, string $value, array $params = [])
+    public function addParameterizedHeader(string $name, string $value, array $params = []): self
     {
         return $this->add(new ParameterizedHeader($name, $value, $params));
     }
@@ -131,7 +131,7 @@ public function has(string $name): bool
     /**
      * @return $this
      */
-    public function add(HeaderInterface $header)
+    public function add(HeaderInterface $header): self
     {
         static $map = [
             'date' => DateHeader::class,