[Fix #840] Allow overriding of default object mapper

By default, the internal object mapper will call findAndRegisterModules.
If this is not the desired behaviour, implementors might replace it by
a custom object mapper of their choice

Signed-off-by: fjtirado <[email protected]>

Author: fjtirado

impl/jackson/src/main/java/io/serverlessworkflow/impl/jackson/JsonUtils.java

@@ -45,6 +45,7 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Optional;
+import java.util.ServiceLoader;
 import java.util.Set;
 import java.util.function.BiConsumer;
 import java.util.function.BinaryOperator;
@@ -54,7 +55,11 @@
 
 public class JsonUtils {
 
-  private static ObjectMapper mapper = new ObjectMapper();
+  private static ObjectMapper mapper =
+      ServiceLoader.load(ObjectMapperFactory.class)
+          .findFirst()
+          .orElseGet(() -> () -> new ObjectMapper().findAndRegisterModules())
+          .get();
 
   public static ObjectMapper mapper() {
     return mapper;

impl/jackson/src/main/java/io/serverlessworkflow/impl/jackson/ObjectMapperFactory.java

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.serverlessworkflow.impl.jackson;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import java.util.function.Supplier;
+
+public interface ObjectMapperFactory extends Supplier<ObjectMapper> {}