fix: skip void methods (fixes #555) (#569)

Author: YanivEidelnantDev

jsonschema-module-jackson/src/main/java/com/github/victools/jsonschema/module/jackson/JsonUnwrappedDefinitionProvider.java

@@ -88,6 +88,10 @@ private boolean hasJsonUnwrappedAnnotation(ResolvedMember<?> member) {
      * @return created schema
      */
     private Optional<ObjectNode> createUnwrappedMemberSchema(ResolvedMember<?> member, SchemaGenerationContext context) {
+        if (member.getType() == null) {
+            // skip void methods (e.g. setters generated by Lombok that inherit @JsonUnwrapped from the field)
+            return Optional.empty();
+        }
         return AnnotationHelper.resolveAnnotation(member, JsonUnwrapped.class, JacksonSchemaModule.NESTED_ANNOTATION_CHECK)
                 .filter(JsonUnwrapped::enabled)
                 .map(annotation -> {