From ea08106c809c17a660c9180210e12ae02c2d5914 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=A9mie=20Bresson?= <dev@jmini.fr>
Date: Tue, 12 Feb 2019 19:27:20 +0100
Subject: [PATCH] [core] Fix NullPointer when schema is not set in header
 (#2133)

---
 .../openapitools/codegen/DefaultCodegen.java  | 15 +++++++++++----
 .../codegen/DefaultCodegenTest.java           | 19 +++++++++++++++++++
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
index 5422042499..6db9d65b22 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
@@ -3297,12 +3297,19 @@ public class DefaultCodegen implements CodegenConfig {
      */
     private void addHeaders(ApiResponse response, List<CodegenProperty> properties) {
         if (response.getHeaders() != null) {
-            for (Map.Entry<String, Header> headers : response.getHeaders().entrySet()) {
-                String description = headers.getValue().getDescription();
+            for (Map.Entry<String, Header> headerEntry : response.getHeaders().entrySet()) {
+                String description = headerEntry.getValue().getDescription();
                 // follow the $ref
-                Header header = ModelUtils.getReferencedHeader(this.openAPI, headers.getValue());
+                Header header = ModelUtils.getReferencedHeader(this.openAPI, headerEntry.getValue());
 
-                CodegenProperty cp = fromProperty(headers.getKey(), header.getSchema());
+                Schema schema;
+                if(header.getSchema() == null) {
+                    LOGGER.warn("No schema defined for Header '" + headerEntry.getKey() +"', using a String schema");
+                    schema = new StringSchema();
+                } else {
+                    schema = header.getSchema();
+                }
+                CodegenProperty cp = fromProperty(headerEntry.getKey(), schema);
                 cp.setDescription(escapeText(description));
                 cp.setUnescapedDescription(description);
                 properties.add(cp);
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/DefaultCodegenTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/DefaultCodegenTest.java
index 63bf869c79..348c41b1f8 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/DefaultCodegenTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/DefaultCodegenTest.java
@@ -22,6 +22,7 @@ import io.swagger.v3.oas.models.OpenAPI;
 import io.swagger.v3.oas.models.Operation;
 import io.swagger.v3.oas.models.PathItem;
 import io.swagger.v3.oas.models.media.*;
+import io.swagger.v3.oas.models.headers.Header;
 import io.swagger.v3.oas.models.parameters.QueryParameter;
 import io.swagger.v3.oas.models.parameters.RequestBody;
 import io.swagger.v3.oas.models.responses.ApiResponse;
@@ -532,6 +533,24 @@ public class DefaultCodegenTest {
         Assert.assertEquals(co2.path, "/some/path");
     }
 
+    @Test
+    public void testResponseWithNoSchemaInHeaders() {
+        OpenAPI openAPI = TestUtils.createOpenAPI();
+        ApiResponse response2XX = new ApiResponse()
+                .description("OK")
+                .addHeaderObject("x-custom-header", new Header()
+                        .description("a custom header")
+                        .style(Header.StyleEnum.SIMPLE));
+        Operation operation1 = new Operation().operationId("op1").responses(new ApiResponses().addApiResponse("2XX", response2XX));
+        openAPI.path("/here", new PathItem().get(operation1));
+        final DefaultCodegen codegen = new DefaultCodegen();
+        codegen.setOpenAPI(openAPI);
+
+        CodegenResponse cr = codegen.fromResponse("2XX", response2XX);
+        Assert.assertNotNull(cr);
+        Assert.assertTrue(cr.hasHeaders);
+    }
+
     private void verifyPersonDiscriminator(CodegenDiscriminator discriminator) {
         CodegenDiscriminator test = new CodegenDiscriminator();
         test.setPropertyName("DollarUnderscoretype");