Fixing NPEs when schemas are referenced and not directly included in the specification of a sse endpoint. Fixes #17271

Author: kgeilmann

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/SpringCodegen.java

@@ -70,6 +70,7 @@
 import org.openapitools.codegen.templating.mustache.SplitStringLambda;
 import org.openapitools.codegen.templating.mustache.SpringHttpStatusLambda;
 import org.openapitools.codegen.templating.mustache.TrimWhitespaceLambda;
+import org.openapitools.codegen.utils.ModelUtils;
 import org.openapitools.codegen.utils.ProcessUtils;
 import org.openapitools.codegen.utils.URLPathUtils;
 import org.slf4j.Logger;
@@ -1044,6 +1045,7 @@ public CodegenOperation fromOperation(String path, String httpMethod, Operation
                         .filter(p -> p.getRight().is2xx) // consider only success
                         .map(p -> p.getLeft().getContent().get(MEDIA_EVENT_STREAM))
                         .map(MediaType::getSchema)
+                        .map(s -> ModelUtils.unaliasSchema(openAPI, s))
                         .collect(Collectors.toList()).stream()
                         .collect(Collectors.groupingBy(Schema::getType));
                 if(schemaTypes.containsKey("array")) {

modules/openapi-generator/src/test/java/org/openapitools/codegen/java/spring/SpringCodegenTest.java

@@ -4496,17 +4496,15 @@ public void testSSEOperationSupport() throws Exception {
                       .assertMethod("sse2", "ServerWebExchange")
                       .hasReturnType("Flux<EventType>")
                       .toFileAssert()
-                      // FIXME: Generator Crash
-                      // .assertMethod("sse3", "ServerWebExchange")
-                      // .hasReturnType("Flux<String>")
-                      // .toFileAssert()
+                      .assertMethod("sse3", "ServerWebExchange")
+                      .hasReturnType("Flux<String>")
+                      .toFileAssert()
                       .assertMethod("sse4", "ServerWebExchange")
                       .hasReturnType("Flux<String>")
                       .toFileAssert()
-                      // FIXME: Generator Crash, see #17271
-                      // .assertMethod("sse5", "ServerWebExchange")
-                      // .hasReturnType("Flux<EventType>")
-                      // .toFileAssert()
+                      .assertMethod("sse5", "ServerWebExchange")
+                      .hasReturnType("Flux<EventType>")
+                      .toFileAssert()
 
                       // FIXME: Generator Crash
                       // .assertMethod("notSse1", "ServerWebExchange")
@@ -4539,20 +4537,18 @@ public void testSSEOperationSupport() throws Exception {
                       .hasReturnType("Flux<EventType>")
                       .bodyContainsLines("return Flux.empty();")
                       .toFileAssert()
-                      // FIXME: Generator Crash
-                      // .assertMethod("sse3", "ServerWebExchange")
-                      // .hasReturnType("Flux<String>")
-                      // .bodyContainsLines("return Flux.empty();")
-                      // .toFileAssert()
+                      .assertMethod("sse3", "ServerWebExchange")
+                      .hasReturnType("Flux<String>")
+                      .bodyContainsLines("return Flux.empty();")
+                      .toFileAssert()
                       .assertMethod("sse4", "ServerWebExchange")
                       .hasReturnType("Flux<String>")
                       .bodyContainsLines("return Flux.empty();")
                       .toFileAssert()
-                      // FIXME: Generator Crash
-                      // .assertMethod("sse5", "ServerWebExchange")
-                      // .hasReturnType("Flux<String>")
-                      // .bodyContainsLines("return Flux.empty();")
-                      // .toFileAssert()
+                      .assertMethod("sse5", "ServerWebExchange")
+                      .hasReturnType("Flux<EventType>")
+                      .bodyContainsLines("return Flux.empty();")
+                      .toFileAssert()
 
                       // FIXME: Generator Crash
                       // .assertMethod("notSse1", "ServerWebExchange")

modules/openapi-generator/src/test/resources/3_0/sse.yaml

@@ -34,31 +34,29 @@ paths:
                 format: event-stream
                 items:
                   $ref: "#/components/schemas/EventType"
-  # FIXME: Generator Crash
-  #  /path/sse/3:
-  #      get:
-  #        operationId: sse_3
-  #        responses:
-  #          "200":
-  #            description: using reference for schema
-  #            content:
-  #              text/event-stream:
-  #                schema:
-  #                  $ref: "#/components/schemas/EventTypeStream"
+  /path/sse/3:
+    get:
+      operationId: sse_3
+      responses:
+        "200":
+          description: using reference for schema
+          content:
+            text/event-stream:
+              schema:
+                $ref: "#/components/schemas/Stream"
   /path/sse/4:
     get:
       operationId: sse_4
       responses:
         "200":
-          $ref: "#/components/responses/EventTypeResponse"
-  # FIXME: generator crash
-  #  /path/sse/5:
-  #    post:
-  #      operationId: sse_5
-  #      description: indirect references, see Issue 17271
-  #      responses:
-  #        '200':
-  #          $ref: '#/components/responses/EventTypeResponseWithReference'
+          $ref: "#/components/responses/StreamResponse"
+  /path/sse/5:
+    post:
+      operationId: sse_5
+      description: indirect references, see Issue 17271
+      responses:
+        '200':
+          $ref: '#/components/responses/StreamResponseWithReference'
 
   # FIXME: generator crash
   #  /path/notsse/1:
@@ -132,6 +130,11 @@ components:
         attribute1:
           type: string
     EventTypeStream:
+      type: array
+      format: event-stream
+      items:
+        $ref: '#/components/schemas/EventType'
+    Stream:
       type: array
       format: event-stream
       items:
@@ -142,7 +145,7 @@ components:
 
 
   responses:
-    EventTypeResponse:
+    StreamResponse:
       description: response
       content:
         text/event-stream:
@@ -152,8 +155,8 @@ components:
             items:
               type: string
 
-    EventTypeResponseWithReference:
-      description: acknowledged
+    StreamResponseWithReference:
+      description: response
       content:
         text/event-stream:
           schema: