Add example and examples to @Header annotation and verify in TCK

Signed-off-by: Michael Edgar <michael@xlate.io>

Author: MikeEdgar

api/src/main/java/org/eclipse/microprofile/openapi/annotations/headers/Header.java

@@ -23,10 +23,18 @@
 import java.lang.annotation.Target;
 
 import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+import org.eclipse.microprofile.openapi.annotations.media.ExampleObject;
 import org.eclipse.microprofile.openapi.annotations.media.Schema;
 
 /**
- * Describes a single header object
+ * Describes a single header object.
+ * <p>
+ * Note that although the {@linkplain #org.eclipse.microprofile.openapi.models.headers.Header header} model contains a
+ * {@link org.eclipse.microprofile.openapi.models.headers.Header#getContent() content} property, modeling that
+ * information using annotations is not possible because the content annotation's
+ * {@link org.eclipse.microprofile.openapi.annotations.media.Content#encoding() encoding} references this annotation, a
+ * cycle disallowed by the Java language.
+ * </p>
  *
  * @see <a href= "https://spec.openapis.org/oas/v3.1.0.html#header-object">OpenAPI Specification Header Object</a>
  **/
@@ -102,4 +110,30 @@
      * @since 3.1
      */
     Extension[] extensions() default {};
+
+    /**
+     * Example of the header's potential value. The example SHOULD match the specified schema and encoding properties if
+     * present. The {@code example} field is mutually exclusive of the {@link #examples() examples} field. Furthermore,
+     * if referencing a {@link #schema() schema} that contains an example, the {@code example} value SHALL override the
+     * example provided by the schema. To represent examples of media types that cannot naturally be represented in JSON
+     * or YAML, a string value can contain the example with escaping where necessary.
+     *
+     * @return an example of the header
+     *
+     * @since 4.2
+     **/
+    String example() default "";
+
+    /**
+     * Examples of the header's potential value. Each example SHOULD contain a value in the correct format as specified
+     * in the parameter encoding. The {@code examples} field is mutually exclusive of the {@link #example() example}
+     * field. Furthermore, if referencing a schema that contains an example, the {@code examples} value SHALL override
+     * the example provided by the schema.
+     *
+     * @return the list of examples for this header
+     *
+     * @since 4.2
+     **/
+    ExampleObject[] examples() default {};
+
 }

api/src/main/java/org/eclipse/microprofile/openapi/annotations/headers/package-info.java

@@ -26,6 +26,6 @@
  * </pre>
  */
 
-@org.osgi.annotation.versioning.Version("1.1")
+@org.osgi.annotation.versioning.Version("1.2")
 @org.osgi.annotation.versioning.ProviderType
-package org.eclipse.microprofile.openapi.annotations.headers;
+package org.eclipse.microprofile.openapi.annotations.headers;

spec/src/main/asciidoc/release_notes.asciidoc

@@ -19,6 +19,16 @@
 [[release_notes]]
 == Release Notes
 
+[[release_notes_42]]
+=== Release Notes for MicroProfile OpenAPI 4.2
+
+A full list of changes delivered in the 4.2 release can be found at link:https://github.com/microprofile/microprofile-open-api/milestone/14?closed=1[MicroProfile OpenAPI 4.2 Milestone]
+
+[[api_changes_42]]
+==== API/SPI changes
+
+* Add `example` and `examples` to `@Header` and verify implementation support in TCK (https://github.com/microprofile/microprofile-open-api/issues/697)[697])
+
 [[release_notes_41]]
 === Release Notes for MicroProfile OpenAPI 4.1
 

tck/src/main/java/org/eclipse/microprofile/openapi/apps/airlines/resources/UserResource.java

@@ -205,7 +205,18 @@ public Response updateUser(
 
     @PATCH
     @Path("/username/{username}")
-    @APIResponse(responseCode = "200", description = "Password was changed successfully")
+    @APIResponse(responseCode = "200", description = "Password was changed successfully", headers = {
+            @Header(name = "X-Password-Strength", description = "Rating of the strength of the new password value.",
+                    schema = @Schema(type = SchemaType.NUMBER), examples = {
+                            @ExampleObject(name = "strong", summary = "Password is strong", value = "10"),
+                            @ExampleObject(name = "adequate", summary = "Password is adequate", value = "8.5"),
+                            @ExampleObject(name = "weak", summary = "Password is weak", value = "5.1"),
+                    })
+    })
+    @APIResponse(responseCode = "400", description = "New password is too weak", headers = {
+            @Header(name = "X-Password-Strength", description = "Rating of the strength of the new password value.",
+                    schema = @Schema(type = SchemaType.NUMBER), example = "0")
+    })
     @Operation(summary = "Change user password", description = "This changes the password for the logged in user.",
                operationId = "changePassword")
     @SecurityRequirementsSet(value = {

tck/src/main/java/org/eclipse/microprofile/openapi/tck/AirlinesAppTest.java

@@ -32,6 +32,7 @@
 import static org.hamcrest.Matchers.hasItems;
 import static org.hamcrest.Matchers.hasKey;
 import static org.hamcrest.Matchers.hasSize;
+import static org.hamcrest.Matchers.hasToString;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.not;
 import static org.hamcrest.Matchers.notNullValue;
@@ -312,10 +313,10 @@ public void testAPIResponse(String type) {
         vr.body("paths.'/user/username/{username}'.delete.responses.'404'.description", equalTo("User not found"));
 
         // @APIResponse at class level combined with method level
-        vr.body("paths.'/user/username/{username}'.patch.responses", aMapWithSize(2));
-        vr.body("paths.'/user/username/{username}'.patch.responses.'200'.description",
-                equalTo("Password was changed successfully"));
-        vr.body("paths.'/user/username/{username}'.patch.responses.'400'.description", equalTo("Invalid request"));
+        vr.body("paths.'/user/logout'.get.responses", aMapWithSize(2));
+        vr.body("paths.'/user/logout'.get.responses.'200'.description",
+                equalTo("Successful user logout."));
+        vr.body("paths.'/user/logout'.get.responses.'400'.description", equalTo("Invalid request"));
     }
 
     @Test(dataProvider = "formatProvider")
@@ -832,6 +833,27 @@ public void testExampleObject(String type) {
                 equalTo("bsmith"));
     }
 
+    @Test(dataProvider = "formatProvider")
+    public void testExamplesInHeaders(String type) {
+        ValidatableResponse vr = callEndpoint(type);
+
+        // Multiple examples in Header
+        vr.body("paths.'/user/username/{username}'.patch.responses.'200'.headers.'X-Password-Strength'",
+                hasKey("examples"));
+
+        // Implementations MAY parse the example to the data type of the schema, so here we leniently test
+        // the value as a string using String#valueOf (via hasToString).
+
+        vr.body("paths.'/user/username/{username}'.patch.responses.'200'.headers.'X-Password-Strength'.examples", allOf(
+                hasEntry(equalTo("strong"), hasEntry(equalTo("value"), hasToString("10"))),
+                hasEntry(equalTo("adequate"), hasEntry(equalTo("value"), hasToString("8.5"))),
+                hasEntry(equalTo("weak"), hasEntry(equalTo("value"), hasToString("5.1")))));
+
+        // Single example in header
+        vr.body("paths.'/user/username/{username}'.patch.responses.'400'.headers.'X-Password-Strength'",
+                hasEntry(equalTo("example"), hasToString("0")));
+    }
+
     @Test(dataProvider = "formatProvider")
     public void testContentExampleAttribute(String type) {
         ValidatableResponse vr = callEndpoint(type);