refactor: message properties

Signed-off-by: Sebastian Krupinski <krupinski01@gmail.com>

lib/Providers/MessageAttachment.php

@@ -121,10 +121,20 @@ class MessageAttachment implements MessagePartInterface {
 
     public function getBlobId(): ?string { return $this->_meta->getBlobId(); }
     public function getId(): ?string { return $this->_meta->getId(); }
+    public function getSize(): ?int { return $this->_meta->getSize(); }
     public function getDisposition(): ?string { return $this->_meta->getDisposition(); }
+    public function getContentId(): ?string { return $this->_meta->getContentId(); }
     public function getCharset(): ?string { return $this->_meta->getCharset(); }
     public function getLanguage(): ?string { return $this->_meta->getLanguage(); }
     public function getLocation(): ?string { return $this->_meta->getLocation(); }
+    public function getContent(): ?string { return $this->_contents; }
     public function getParts(): array { return $this->_meta->getParts(); }
-    public function jsonSerialize(): array { return $this->_meta->jsonSerialize(); }
+    public function jsonSerialize(): array {
+        $data = $this->_meta->jsonSerialize();
+        if ($this->_contents !== null) {
+            $data['content'] = $this->_contents;
+        }
+
+        return $data;
+    }
 }