Follow up for #620: pass correct expand_empty_elements to the new serializers

Author: Mingun

src/se/content.rs

@@ -88,7 +88,7 @@ impl<'w, 'i, W: Write> ContentSerializer<'w, 'i, W> {
             level: self.level,
             indent: self.indent.borrow(),
             write_indent: self.write_indent,
-            expand_empty_elements: false,
+            expand_empty_elements: self.expand_empty_elements,
         }
     }
 

src/se/element.rs

@@ -397,7 +397,7 @@ impl<'w, 'k, W: Write> Struct<'w, 'k, W> {
             level: self.ser.ser.level,
             indent: self.ser.ser.indent.borrow(),
             write_indent: true,
-            expand_empty_elements: false,
+            expand_empty_elements: self.ser.ser.expand_empty_elements,
         };
 
         if key == TEXT_KEY {