From 74cdb4d36d459601824a89311b6a00378cc21d9f Mon Sep 17 00:00:00 2001
From: Michael Edgar <michael@xlate.io>
Date: Wed, 11 Dec 2024 09:52:59 -0500
Subject: [PATCH] Handle Kotlin `Flow` as a wrapper type

Signed-off-by: Michael Edgar <michael@xlate.io>
---
 .../api/constants/KotlinConstants.java        |  3 ++
 .../openapi/runtime/util/TypeUtil.java        |  1 +
 testsuite/data/pom.xml                        | 30 ++++++++++++++++++-
 .../openapi/testdata/kotlin/KotlinResource.kt | 25 ++++++++++++++++
 .../testdata/QuarkusAnnotationScanIT.java     | 11 +++++++
 ...ponents.schemas.kotlin-flow-unwrapped.json | 21 +++++++++++++
 6 files changed, 90 insertions(+), 1 deletion(-)
 create mode 100644 testsuite/data/src/main/kotlin/io/smallrye/openapi/testdata/kotlin/KotlinResource.kt
 create mode 100644 testsuite/data/src/test/resources/io/smallrye/openapi/testdata/components.schemas.kotlin-flow-unwrapped.json

diff --git a/core/src/main/java/io/smallrye/openapi/api/constants/KotlinConstants.java b/core/src/main/java/io/smallrye/openapi/api/constants/KotlinConstants.java
index c19e051a6..afe9d5461 100644
--- a/core/src/main/java/io/smallrye/openapi/api/constants/KotlinConstants.java
+++ b/core/src/main/java/io/smallrye/openapi/api/constants/KotlinConstants.java
@@ -21,6 +21,9 @@ public class KotlinConstants {
     public static final DotName JETBRAINS_NOT_NULL = DotName
             .createSimple("org.jetbrains.annotations.NotNull");
 
+    public static final DotName FLOW = DotName
+            .createSimple("kotlinx.coroutines.flow.Flow");
+
     private KotlinConstants() {
     }
 }
diff --git a/core/src/main/java/io/smallrye/openapi/runtime/util/TypeUtil.java b/core/src/main/java/io/smallrye/openapi/runtime/util/TypeUtil.java
index 7ed7d583c..94d3b71cb 100644
--- a/core/src/main/java/io/smallrye/openapi/runtime/util/TypeUtil.java
+++ b/core/src/main/java/io/smallrye/openapi/runtime/util/TypeUtil.java
@@ -310,6 +310,7 @@ public class TypeUtil {
         jdkIndex = indexer.complete();
 
         wrapperTypes.addAll(JaxbConstants.JAXB_ELEMENT);
+        wrapperTypes.add(KotlinConstants.FLOW);
         wrapperTypes.add(MutinyConstants.UNI_TYPE.name());
         wrapperTypes.add(JDKConstants.COMPLETION_STAGE_NAME);
         wrapperTypes.add(JDKConstants.COMPLETABLE_FUTURE_NAME);
diff --git a/testsuite/data/pom.xml b/testsuite/data/pom.xml
index 1e3592dfe..d18e54990 100644
--- a/testsuite/data/pom.xml
+++ b/testsuite/data/pom.xml
@@ -14,7 +14,7 @@
 
     <properties>
         <eclipse.microprofile.openapi.version>4.0.2</eclipse.microprofile.openapi.version>
-        <kotlin.version>2.1.0</kotlin.version>
+        <kotlin.version>2.0.21</kotlin.version>
         <java.version>17</java.version>
         <maven.compiler.source>${java.version}</maven.compiler.source>
         <maven.compiler.target>${java.version}</maven.compiler.target>
@@ -99,6 +99,10 @@
             <groupId>org.jetbrains.kotlin</groupId>
             <artifactId>kotlin-stdlib</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlinx</groupId>
+            <artifactId>kotlinx-coroutines-core</artifactId>
+        </dependency>
 
         <dependency>
             <groupId>io.quarkus</groupId>
@@ -190,7 +194,31 @@
                             </sourceDirs>
                         </configuration>
                     </execution>
+                    <execution>
+                        <id>test-compile</id>
+                        <goals>
+                            <goal>test-compile</goal>
+                        </goals>
+                    </execution>
                 </executions>
+                <configuration>
+                    <compilerPlugins>
+                        <plugin>all-open</plugin>
+                    </compilerPlugins>
+
+                    <pluginOptions>
+                        <!-- Each annotation is placed on its own line -->
+                        <option>all-open:annotation=jakarta.ws.rs.Path</option>
+                    </pluginOptions>
+                </configuration>
+
+                <dependencies>
+                    <dependency>
+                        <groupId>org.jetbrains.kotlin</groupId>
+                        <artifactId>kotlin-maven-allopen</artifactId>
+                        <version>${kotlin.version}</version>
+                    </dependency>
+                </dependencies>
             </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
diff --git a/testsuite/data/src/main/kotlin/io/smallrye/openapi/testdata/kotlin/KotlinResource.kt b/testsuite/data/src/main/kotlin/io/smallrye/openapi/testdata/kotlin/KotlinResource.kt
new file mode 100644
index 000000000..097c2bdf1
--- /dev/null
+++ b/testsuite/data/src/main/kotlin/io/smallrye/openapi/testdata/kotlin/KotlinResource.kt
@@ -0,0 +1,25 @@
+package io.smallrye.openapi.testdata.kotlin
+
+import jakarta.ws.rs.GET
+import jakarta.ws.rs.Path
+import jakarta.ws.rs.Produces
+import jakarta.ws.rs.core.MediaType
+
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flow
+import org.jboss.resteasy.reactive.RestStreamElementType
+
+@Path("kotlin")
+class KotlinResource {
+    @Path("hello")
+    @GET
+    @Produces(MediaType.SERVER_SENT_EVENTS)
+    @RestStreamElementType(MediaType.APPLICATION_JSON)
+    fun hello(): Flow<String> {
+        return flow {
+            Foobar("Hello")
+        }
+    }
+}
+
+data class Foobar(val data: String)
\ No newline at end of file
diff --git a/testsuite/data/src/test/java/io/smallrye/openapi/testdata/QuarkusAnnotationScanIT.java b/testsuite/data/src/test/java/io/smallrye/openapi/testdata/QuarkusAnnotationScanIT.java
index abd4df92d..96c3d03d2 100644
--- a/testsuite/data/src/test/java/io/smallrye/openapi/testdata/QuarkusAnnotationScanIT.java
+++ b/testsuite/data/src/test/java/io/smallrye/openapi/testdata/QuarkusAnnotationScanIT.java
@@ -108,6 +108,17 @@ void testRecordWithPojoPrefixedRecordComponents() throws Exception {
         assertJsonEquals("components.schemas.prefixed-record-component-names.json", result);
     }
 
+    @Test
+    void testKotlinResourceWithUnwrappedFlowSSE() throws Exception {
+        Index index = Index.of(io.smallrye.openapi.testdata.kotlin.KotlinResource.class);
+        OpenApiAnnotationScanner scanner = new OpenApiAnnotationScanner(emptyConfig(), index);
+
+        OpenAPI result = scanner.scan();
+
+        printToConsole(result);
+        assertJsonEquals("components.schemas.kotlin-flow-unwrapped.json", result);
+    }
+
     @Test
     void testSyntheticClassesAndInterfacesIgnoredByDefault() throws Exception {
         try (InputStream source = getClass().getResourceAsStream("/smallrye-open-api-testsuite-data.idx")) {
diff --git a/testsuite/data/src/test/resources/io/smallrye/openapi/testdata/components.schemas.kotlin-flow-unwrapped.json b/testsuite/data/src/test/resources/io/smallrye/openapi/testdata/components.schemas.kotlin-flow-unwrapped.json
new file mode 100644
index 000000000..37ce6bbde
--- /dev/null
+++ b/testsuite/data/src/test/resources/io/smallrye/openapi/testdata/components.schemas.kotlin-flow-unwrapped.json
@@ -0,0 +1,21 @@
+{
+  "openapi" : "3.1.0",
+  "paths" : {
+    "/kotlin/hello" : {
+      "get" : {
+        "responses" : {
+          "200" : {
+            "description" : "OK",
+            "content" : {
+              "text/event-stream" : {
+                "schema" : {
+                  "type" : "string"
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}