Add xmlNamespace trait support

Author: JordonPhillips

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/integrations/BuiltinsIntegration.java

@@ -37,6 +37,7 @@
 import software.amazon.smithy.docgen.core.interceptors.XmlAttributeInterceptor;
 import software.amazon.smithy.docgen.core.interceptors.XmlFlattenedInterceptor;
 import software.amazon.smithy.docgen.core.interceptors.XmlNameInterceptor;
+import software.amazon.smithy.docgen.core.interceptors.XmlNamespaceInterceptor;
 import software.amazon.smithy.docgen.core.writers.DocWriter;
 import software.amazon.smithy.docgen.core.writers.MarkdownWriter;
 import software.amazon.smithy.utils.CodeInterceptor;
@@ -82,6 +83,7 @@ public List<? extends CodeInterceptor<? extends CodeSection, DocWriter>> interce
                 new ApiKeyAuthInterceptor(),
                 new TimestampFormatInterceptor(),
                 new JsonNameInterceptor(),
+                new XmlNamespaceInterceptor(),
                 new XmlAttributeInterceptor(),
                 new XmlNameInterceptor(),
                 new XmlFlattenedInterceptor(),

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/interceptors/XmlAttributeInterceptor.java

@@ -14,7 +14,7 @@
 
 /**
  * Notes that a member is an
- * <a href="https://smithy.io/2.0/spec/protocol-traits.html#xmlnattribute-trait">
+ * <a href="https://smithy.io/2.0/spec/protocol-traits.html#xmlattribute-trait">
  * xml attribute</a> in the {@link ProtocolSection} if the protocol supports it.
  */
 @SmithyInternalApi
@@ -31,6 +31,7 @@ protected ShapeId getTraitId() {
 
     @Override
     void write(DocWriter writer, String previousText, ProtocolSection section, XmlAttributeTrait trait) {
+        writer.writeWithNoFormatting(previousText + "\n");
         writer.openAdmonition(AdmonitionType.IMPORTANT);
         writer.write("This member represents an XML attribute rather than a nested tag.");
         writer.closeAdmonition();

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/interceptors/XmlNamespaceInterceptor.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.docgen.core.interceptors;
+
+import software.amazon.smithy.docgen.core.sections.ProtocolSection;
+import software.amazon.smithy.docgen.core.writers.DocWriter;
+import software.amazon.smithy.docgen.core.writers.DocWriter.AdmonitionType;
+import software.amazon.smithy.model.shapes.ShapeId;
+import software.amazon.smithy.model.traits.XmlNamespaceTrait;
+import software.amazon.smithy.utils.SmithyInternalApi;
+
+/**
+ * Notes that a member needs an
+ * <a href="https://smithy.io/2.0/spec/protocol-traits.html#xmlnamespace-trait">
+ * xml namespace</a> in the {@link ProtocolSection} if the protocol supports it.
+ */
+@SmithyInternalApi
+public final class XmlNamespaceInterceptor extends ProtocolTraitInterceptor<XmlNamespaceTrait> {
+    @Override
+    protected Class<XmlNamespaceTrait> getTraitClass() {
+        return XmlNamespaceTrait.class;
+    }
+
+    @Override
+    protected ShapeId getTraitId() {
+        return XmlNamespaceTrait.ID;
+    }
+
+    @Override
+    void write(DocWriter writer, String previousText, ProtocolSection section, XmlNamespaceTrait trait) {
+        writer.writeWithNoFormatting(previousText + "\n");
+        var namespace = "xmlns";
+        if (trait.getPrefix().isPresent()) {
+            namespace += ":" + trait.getPrefix().get();
+        }
+        namespace += "=\"" + trait.getUri() + "\"";
+        writer.openAdmonition(AdmonitionType.IMPORTANT);
+        writer.write("""
+                This tag must contain the following XML namespace $`
+                """, namespace);
+        writer.closeAdmonition();
+    }
+}

smithy-docgen-test/model/main.smithy

@@ -182,6 +182,10 @@ structure XmlTraits {
     /// This map uses the non-default flat map behavior.
     @xmlFlattened
     flatMap: StringMap
+
+    /// This string tag needs an xml namespace added to it.
+    @xmlNamespace(prefix: "example", uri: "https://example.com")
+    xmlNamespace: String
 }
 
 list StringList {