Set a null value to attributes remove it from the collection

src/CfdiUtils/Nodes/Attributes.php

@@ -49,7 +49,7 @@ public function exists(string $name): bool
     public function importArray(array $attributes): self
     {
         foreach ($attributes as $key => $value) {
-            $this->set((string) $key, $this->castValueToString($value));
+            $this[$key] = $value;
         }
         return $this;
     }
@@ -79,7 +79,11 @@ public function offsetGet($offset)
 
     public function offsetSet($offset, $value)
     {
-        $this->set((string) $offset, $this->castValueToString($value));
+        if (null === $value) {
+            $this->remove((string) $offset);
+        } else {
+            $this->set((string) $offset, $this->castValueToString($value));
+        }
     }
 
     public function offsetUnset($offset)

tests/CfdiUtilsTests/Nodes/AttributesTest.php

@@ -119,4 +119,26 @@ public function testIterator()
         }
         $this->assertEquals($data, $created);
     }
+
+    public function testSetToNullPerformRemove()
+    {
+        $attributes = new Attributes([
+            'foo' => 'bar',
+        ]);
+        $this->assertTrue($attributes->exists('foo'));
+        $attributes['foo'] = null;
+        $this->assertFalse($attributes->exists('foo'));
+    }
+
+    public function testImportWithNullPerformRemove()
+    {
+        $attributes = new Attributes([
+            'foo' => 'bar',
+        ]);
+        $this->assertTrue($attributes->exists('foo'));
+        $attributes->importArray([
+            'foo' => null,
+        ]);
+        $this->assertFalse($attributes->exists('foo'));
+    }
 }