Revert "xmpp-parsers: Support required in SM feature"

This reverts commit 4e0cd5d96b.

parsers/ChangeLog

@@ -108,8 +108,7 @@ XXXX-YY-ZZ RELEASER <admin@example.com>
       - Push Notifications (XEP-0357) (!543)
       - JSON Containers (XEP-0335) (!546)
     * Improvements:
-      - Add support for `<optional/>` and `<required/>` in XEP-0198 feature
-        advertisment.
+      - Add support for `<optional/> in XEP-0198 feature advertisment
       - Add support application-specific error conditions in XEP-0198
       - Keep unsupported vCard elements as `minidom::Element`, so that they
         get serialized back instead of being dropped.  We now also test for

parsers/src/sasl2.rs

@@ -269,13 +269,7 @@ mod tests {
 
         let inline = auth.inline.unwrap();
         assert_eq!(inline.bind2.unwrap().inline_features.len(), 0);
-        assert_eq!(
-            inline.sm.unwrap(),
-            StreamManagement {
-                optional: false,
-                required: false
-            }
-        );
+        assert_eq!(inline.sm.unwrap(), StreamManagement { optional: false });
         assert_eq!(inline.payloads.len(), 0);
     }
 

parsers/src/sm.rs

@@ -133,7 +133,7 @@ pub struct Resumed {
     pub previd: StreamId,
 }
 
-// TODO: Only allow either optional or required, not both.
+// TODO: add support for optional and required.
 /// Represents availability of Stream Management in `<stream:features/>`.
 #[derive(FromXml, AsXml, PartialEq, Debug, Clone)]
 #[xml(namespace = ns::SM, name = "sm")]
@@ -141,10 +141,6 @@ pub struct StreamManagement {
     /// `<optional/>` flag.
     #[xml(flag)]
     pub optional: bool,
-
-    /// `<required/>` flag.
-    #[xml(flag)]
-    pub required: bool,
 }
 
 /// Application-specific error condition to use when the peer acknowledges
@@ -226,7 +222,7 @@ mod tests {
         assert_size!(R, 0);
         assert_size!(Resume, 16);
         assert_size!(Resumed, 16);
-        assert_size!(StreamManagement, 2);
+        assert_size!(StreamManagement, 1);
         assert_size!(HandledCountTooHigh, 8);
     }
 
@@ -241,7 +237,7 @@ mod tests {
         assert_size!(R, 0);
         assert_size!(Resume, 32);
         assert_size!(Resumed, 32);
-        assert_size!(StreamManagement, 2);
+        assert_size!(StreamManagement, 1);
         assert_size!(HandledCountTooHigh, 8);
     }
 
@@ -255,9 +251,7 @@ mod tests {
     #[test]
     fn stream_feature() {
         let elem: Element = "<sm xmlns='urn:xmpp:sm:3'/>".parse().unwrap();
-        let sm = StreamManagement::try_from(elem).unwrap();
-        assert_eq!(sm.optional, false);
-        assert_eq!(sm.required, false);
+        StreamManagement::try_from(elem).unwrap();
     }
 
     #[test]