fix(JOHNZON-397): sets the maxBigDecimalScale if it's our JsonProvide…

…r impl

Signed-off-by: Jean-Louis Monteiro <jlmonteiro@tomitribe.com>

johnzon-mapper/src/main/java/org/apache/johnzon/mapper/MapperBuilder.java

@@ -23,6 +23,7 @@
 import static java.util.Locale.ROOT;
 
 // import org.apache.johnzon.core.JsonParserFactoryImpl; // don't depend on core in mapper
+import org.apache.johnzon.mapper.util.JsonProviderUtil;
 import org.apache.johnzon.mapper.access.AccessMode;
 import org.apache.johnzon.mapper.access.BaseAccessMode;
 import org.apache.johnzon.mapper.access.FieldAccessMode;
@@ -123,6 +124,7 @@ public Mapper build() {
                 provider = this.provider;
             } else {
                 provider = JsonProvider.provider();
+                JsonProviderUtil.setMaxBigDecimalScale(provider, maxBigDecimalScale);
                 this.provider = provider;
             }
             final Map<String, Object> config = new HashMap<String, Object>();
@@ -141,7 +143,7 @@ public Mapper build() {
             }
 
             if (readerFactory == null) {
-                config.remove(JsonGenerator.PRETTY_PRINTING); // doesnt mean anything anymore for reader
+                config.remove(JsonGenerator.PRETTY_PRINTING); // doesn't mean anything anymore for reader
                 if (supportsComments) {
                     config.put("org.apache.johnzon.supports-comments", "true");
                 }
@@ -158,6 +160,7 @@ public Mapper build() {
             }
         } else if (this.provider == null) {
             this.provider = JsonProvider.provider();
+            JsonProviderUtil.setMaxBigDecimalScale(provider, maxBigDecimalScale);
         }
         if (builderFactory == null) {
             builderFactory = provider.createBuilderFactory(emptyMap());

johnzon-mapper/src/main/java/org/apache/johnzon/mapper/util/JsonProviderUtil.java

@@ -0,0 +1,67 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.johnzon.mapper.util;
+
+import jakarta.json.spi.JsonProvider;
+import org.apache.johnzon.core.JsonProviderImpl;
+
+import java.lang.reflect.Method;
+
+/**
+ * ClassLoader related utils to avoid direct access to our JSON provider from the mapper
+ */
+public final class JsonProviderUtil {
+
+    private final static Method SET_MAX_BIG_DECIMAL_SCALE;
+
+    static {
+        try {
+            SET_MAX_BIG_DECIMAL_SCALE =
+                JsonProviderImpl.class.getDeclaredMethod("setMaxBigDecimalScale", Integer.TYPE);
+            SET_MAX_BIG_DECIMAL_SCALE.setAccessible(true);
+        } catch (final NoSuchMethodException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private JsonProviderUtil() {
+        // private utility class ct
+    }
+
+    /**
+     * Sets the max big decimal scale property on the given provider instance.
+     * <p>
+     * This method is intentionally not receiving the property name, so we know exactly what will be passed in and what
+     * the method is supposed to set on the provider.
+     * <p>
+     * If the provider is not an instance of our JohnzonProviderImpl (org.apache.johnzon.core.JsonProviderImpl), the
+     * method is a noop.
+     *
+     * @param provider the provider to configure. Must be an instance of org.apache.johnzon.core.JsonProviderImpl
+     * @param value the max big decimal scale to set on the provider
+     */
+    public static void setMaxBigDecimalScale(final JsonProvider provider, final int value) {
+        if (!"org.apache.johnzon.core.JsonProviderImpl".equals(provider.getClass().getName())) return;
+
+        try {
+            SET_MAX_BIG_DECIMAL_SCALE.invoke(provider, value);
+        } catch (final Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+}