fix(core): handle nullable schema in NamedSchemaObject

springwolf-core/src/main/java/io/github/springwolf/core/asyncapi/scanners/common/AsyncAnnotationScanner.java

@@ -105,7 +105,7 @@ protected MessageObject buildMessage(AsyncOperation operationData, Method method
                 .build());
 
         String description = operationData.message().description();
-        if (!StringUtils.hasText(description)) {
+        if (!StringUtils.hasText(description) && payloadSchema.schema() != null) {
             description = payloadSchema.schema().getDescription();
         }
         if (StringUtils.hasText(description)) {
@@ -116,7 +116,7 @@ protected MessageObject buildMessage(AsyncOperation operationData, Method method
         var builder = MessageObject.builder()
                 .messageId(payloadSchema.name())
                 .name(payloadSchema.name())
-                .title(payloadSchema.schema().getTitle())
+                .title(payloadSchema.title())
                 .description(description)
                 .payload(messagePayload)
                 .headers(MessageHeaders.of(MessageReference.toSchema(headerSchemaName)))

springwolf-core/src/main/java/io/github/springwolf/core/asyncapi/scanners/common/ClassLevelAnnotationScanner.java

@@ -93,7 +93,7 @@ protected MessageObject buildMessage(ClassAnnotation classAnnotation, NamedSchem
         MessageObject message = MessageObject.builder()
                 .messageId(payloadSchema.name())
                 .name(payloadSchema.name())
-                .title(payloadSchema.schema().getTitle())
+                .title(payloadSchema.title())
                 .description(null)
                 .payload(payload)
                 .headers(MessageHeaders.of(MessageReference.toSchema(headerSchemaName)))

springwolf-core/src/main/java/io/github/springwolf/core/asyncapi/scanners/common/MethodLevelAnnotationScanner.java

@@ -40,7 +40,7 @@ protected MessageObject buildMessage(MethodAnnotation annotation, NamedSchemaObj
         MessageObject message = MessageObject.builder()
                 .messageId(payloadSchema.name())
                 .name(payloadSchema.name())
-                .title(payloadSchema.schema().getTitle())
+                .title(payloadSchema.title())
                 .description(null)
                 .payload(payload)
                 .headers(MessageHeaders.of(MessageReference.toSchema(headerModelName)))

springwolf-core/src/main/java/io/github/springwolf/core/asyncapi/scanners/common/payload/NamedSchemaObject.java

@@ -2,10 +2,15 @@
 package io.github.springwolf.core.asyncapi.scanners.common.payload;
 
 import io.github.springwolf.asyncapi.v3.model.schema.SchemaObject;
+import jakarta.annotation.Nullable;
 
 /**
  * Encapsulates the resolved name for the contained schema.
  * @param name The fully qualified name or the simple name of the schema.
  * @param schema The SchemaObject.
  */
-public record NamedSchemaObject(String name, SchemaObject schema) {}
+public record NamedSchemaObject(String name, @Nullable SchemaObject schema) {
+    public String title() {
+        return schema != null ? schema.getTitle() : name();
+    }
+}

springwolf-core/src/main/java/io/github/springwolf/core/asyncapi/scanners/common/payload/PayloadService.java

@@ -68,7 +68,11 @@ public String extractSchemaForName(Class<?> payloadType) {
     }
 
     private NamedSchemaObject useUnusedPayload() {
-        this.componentsService.registerSchema(PAYLOAD_NOT_USED.schema());
+        SchemaObject schema = PAYLOAD_NOT_USED.schema();
+        if (schema != null) {
+            this.componentsService.registerSchema(schema);
+        }
+
         return PAYLOAD_NOT_USED;
     }
 }

springwolf-plugins/springwolf-kafka-plugin/src/main/java/io/github/springwolf/plugins/kafka/asyncapi/scanners/common/header/AsyncHeadersForKafkaBuilder.java

@@ -9,8 +9,7 @@
 public class AsyncHeadersForKafkaBuilder implements AsyncHeadersBuilder {
     @Override
     public SchemaObject buildHeaders(NamedSchemaObject payloadSchema) {
-        return new AsyncHeadersForSpringKafkaBuilder(
-                        "SpringKafkaDefaultHeaders-" + payloadSchema.schema().getTitle())
+        return new AsyncHeadersForSpringKafkaBuilder("SpringKafkaDefaultHeaders-" + payloadSchema.title())
                 .withTypeIdHeader(payloadSchema.name())
                 .build();
     }