Feature/33 fix npe (#36)

* wip

* Fix NPE

* Fix wording

Author: kevinwallimann

library/src/main/scala/za/co/absa/springdocopenapiscala/OpenAPIScalaCustomizer.scala

@@ -38,13 +38,16 @@ class OpenAPIScalaCustomizer(components: Components) extends OpenApiCustomizer {
       allOperations.foreach { case (_, operation) =>
         val responses = operation.getResponses.asScala
         responses.foreach { case (_, response) =>
-          val isReturningUnit = response.getContent.asScala.exists(
-            _._2.getSchema.get$ref == "#/components/schemas/BoxedUnit"
-          )
-          if (isReturningUnit) response.setContent(None.orNull)
+          val contentOpt = Option(response.getContent)
+          contentOpt.map(_.asScala.foreach { case (_, mediaType) =>
+            val schemaOpt = Option(mediaType.getSchema)
+            schemaOpt.map { schema =>
+              val isReturningUnit = schema.get$ref == "#/components/schemas/BoxedUnit"
+              if (isReturningUnit) response.setContent(None.orNull)
+            }
+          })
         }
       }
     }
   }
-
 }

library/src/test/scala/za/co/absa/springdocopenapiscala/OpenAPIScalaCustomizerSpec.scala

@@ -80,4 +80,72 @@ class OpenAPIScalaCustomizerSpec extends AnyFlatSpec {
     )
   }
 
+  it should "do nothing if a response doesn't have content" in {
+    val components = new Components()
+    val openAPIScalaCustomizer = new OpenAPIScalaCustomizer(components)
+
+    val openAPI = new OpenAPI()
+      .paths(
+        new Paths()
+          .addPathItem(
+            "/api/endpoint",
+            new PathItem()
+              .delete(
+                new Operation()
+                  .responses(
+                    new ApiResponses()
+                      .addApiResponse(
+                        "204",
+                        new ApiResponse()
+                          .description("No Content")
+                      )
+                  )
+              )
+          )
+      )
+
+    openAPIScalaCustomizer.customise(openAPI)
+
+    assert(
+      Option(openAPI.getPaths.get("/api/endpoint").getDelete.getResponses.get("204").getContent).isEmpty
+    )
+  }
+
+  it should "do nothing if a response doesn't have a schema" in {
+    val components = new Components()
+    val openAPIScalaCustomizer = new OpenAPIScalaCustomizer(components)
+
+    val openAPI = new OpenAPI()
+      .paths(
+        new Paths()
+          .addPathItem(
+            "/api/endpoint",
+            new PathItem()
+              .delete(
+                new Operation()
+                  .responses(
+                    new ApiResponses()
+                      .addApiResponse(
+                        "204",
+                        new ApiResponse()
+                          .content(
+                            new Content()
+                              .addMediaType(
+                                "*/*",
+                                new MediaType()
+                              )
+                          )
+                      )
+                  )
+              )
+          )
+      )
+
+    openAPIScalaCustomizer.customise(openAPI)
+
+    assert(
+      Option(openAPI.getPaths.get("/api/endpoint").getDelete.getResponses.get("204").getContent).isDefined
+    )
+  }
+
 }