Merge pull request #5803 from Grzegorz Poznachowski

* gh-5803:
  Apply standard Jackson2ObjectMapperBuilder config via a customizer
  Make it easier to customize auto-configured Jackson2ObjectMapperBuilder

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jackson/Jackson2ObjectMapperBuilderCustomizer.java

+/*
+ * Copyright 2012-2016 the original author or 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 org.springframework.boot.autoconfigure.jackson;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
+
+/**
+ * Callback interface that can be implemented by beans wishing to further customize the
+ * {@link ObjectMapper} via {@link Jackson2ObjectMapperBuilder} retaining its default
+ * auto-configuration.
+ *
+ * @author Grzegorz Poznachowski
+ * @since 1.4.0
+ */
+public interface Jackson2ObjectMapperBuilderCustomizer {
+
+	/**
+	 * Customize the jacksonObjectMapperBuilder.
+	 * @param jacksonObjectMapperBuilder the jacksonObjectMapperBuilder to customize
+	 */
+	void customize(Jackson2ObjectMapperBuilder jacksonObjectMapperBuilder);
+}

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jackson/JacksonAutoConfigurationTests.java

@@ -72,6 +72,7 @@ import static org.mockito.Mockito.mock;
  * @author Marcel Overdijk
  * @author Sebastien Deleuze
  * @author Johannes Edmeier
+ * @author Grzegorz Poznachowski
  */
 public class JacksonAutoConfigurationTests {
 
@@ -419,6 +420,15 @@ public class JacksonAutoConfigurationTests {
 				.isEqualTo("\"Koordinierte Universalzeit\"");
 	}
 
+	@Test
+	public void additionalJacksonBuilderCustomization() throws Exception {
+		this.context.register(JacksonAutoConfiguration.class,
+				ObjectMapperBuilderCustomConfig.class);
+		this.context.refresh();
+		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		assertThat(mapper.getDateFormat()).isInstanceOf(MyDateFormat.class);
+	}
+
 	@Test
 	public void parameterNamesModuleIsAutoConfigured() {
 		assertParameterNamesModuleCreatorBinding(Mode.DEFAULT,
@@ -510,6 +520,22 @@ public class JacksonAutoConfigurationTests {
 
 	}
 
+	@Configuration
+	protected static class ObjectMapperBuilderCustomConfig {
+
+		@Bean
+		public Jackson2ObjectMapperBuilderCustomizer customDateFormat() {
+			return new Jackson2ObjectMapperBuilderCustomizer() {
+				@Override
+				public void customize(
+						Jackson2ObjectMapperBuilder jackson2ObjectMapperBuilder) {
+					jackson2ObjectMapperBuilder.dateFormat(new MyDateFormat());
+				}
+			};
+		}
+
+	}
+
 	protected static final class Foo {
 
 		private String name;