fix: handle null schemaType in assignType for composed schemas

springwolf-core/src/main/java/io/github/springwolf/core/asyncapi/schemas/SwaggerSchemaMapper.java

@@ -207,7 +207,7 @@ private static void assignType(Schema swaggerSchema, SchemaObject.SchemaObjectBu
         String schemaType = swaggerSchema.getType();
         if (!types.contains(schemaType)) {
             // required while swagger v2 does not populate types
-            builder.type(Set.of(schemaType));
+            builder.type(schemaType == null ? Set.of() : Set.of(schemaType));
             return;
         }
 

springwolf-core/src/test/java/io/github/springwolf/core/asyncapi/components/SwaggerSchemaMapperTest.java

@@ -223,6 +223,21 @@ void mapType() {
             assertThat(componentSchema.getSchema().getType()).containsExactly(schema.getType());
         }
 
+        @Test
+        void mapNullTypeForComposedSchema() {
+            // given
+            Schema<?> schema = new Schema<>();
+            // no type set - simulates a composed schema (allOf/oneOf/anyOf) with null type
+            schema.addAllOfItem(new Schema<>());
+
+            // when
+            ComponentSchema componentSchema = swaggerSchemaMapper.mapSchema(schema);
+
+            // then - should not throw NPE, type should be empty
+            assertThat(componentSchema.getSchema()).isNotNull();
+            assertThat(componentSchema.getSchema().getType()).isNullOrEmpty();
+        }
+
         @Test
         void mapProperties() {
             // given
@@ -639,6 +654,7 @@ void mapMaxItems() {
 
     @Nested
     class MapToSwagger {
+
         @Test
         void mapNameAndTitle() {
             // given