Add auto-configuration for Jackson's parameter names module

The parameter names module allows users of Java 8 that have compiled
their code with the -parameters option to avoid the name for
annotations to map the json onto constructor and method parameters
with the names of the parameters being used instead.

This commit adds auto-configuration for the module that will only
be enabled when running on Java 8.

Closes gh-3804

spring-boot-autoconfigure/pom.xml

@@ -55,6 +55,10 @@
 			<artifactId>jackson-datatype-jsr310</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>com.fasterxml.jackson.module</groupId>
+			<artifactId>jackson-module-parameter-names</artifactId>
+		</dependency>
 		<dependency>
 			<groupId>com.google.code.gson</groupId>
 			<artifactId>gson</artifactId>

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

@@ -33,6 +33,8 @@ import org.springframework.beans.factory.BeanFactoryUtils;
 import org.springframework.beans.factory.ListableBeanFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnJava;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnJava.JavaVersion;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.ApplicationContext;
@@ -44,12 +46,14 @@ import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ReflectionUtils;
 
+import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.databind.Module;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.PropertyNamingStrategy;
 import com.fasterxml.jackson.databind.module.SimpleModule;
 import com.fasterxml.jackson.datatype.joda.cfg.JacksonJodaDateFormat;
 import com.fasterxml.jackson.datatype.joda.ser.DateTimeSerializer;
+import com.fasterxml.jackson.module.paramnames.ParameterNamesModule;
 
 /**
  * Auto configuration for Jackson. The following auto-configuration will get applied:
@@ -129,6 +133,19 @@ public class JacksonAutoConfiguration {
 
 	}
 
+	@Configuration
+	@ConditionalOnJava(JavaVersion.EIGHT)
+	@ConditionalOnClass(ParameterNamesModule.class)
+	static class ParameterNamesModuleConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean(ParameterNamesModule.class)
+		public ParameterNamesModule parametersNameModule() {
+			return new ParameterNamesModule(JsonCreator.Mode.PROPERTIES);
+		}
+
+	}
+
 	@Configuration
 	@ConditionalOnClass({ ObjectMapper.class, Jackson2ObjectMapperBuilder.class })
 	@EnableConfigurationProperties(JacksonProperties.class)

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

@@ -37,6 +37,8 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Primary;
 import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
 
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonCreator.Mode;
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.core.JsonGenerator;
 import com.fasterxml.jackson.core.JsonParser;
@@ -50,8 +52,10 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.PropertyNamingStrategy.LowerCaseWithUnderscoresStrategy;
 import com.fasterxml.jackson.databind.SerializationFeature;
 import com.fasterxml.jackson.databind.SerializerProvider;
+import com.fasterxml.jackson.databind.introspect.Annotated;
 import com.fasterxml.jackson.databind.module.SimpleModule;
 import com.fasterxml.jackson.databind.util.StdDateFormat;
+import com.fasterxml.jackson.module.paramnames.ParameterNamesModule;
 
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.hasItem;
@@ -412,6 +416,28 @@ public class JacksonAutoConfigurationTests {
 				objectMapper.writeValueAsString(dateTime));
 	}
 
+	@Test
+	public void parameterNamesModuleIsAutoConfigured() {
+		assertParameterNamesModuleCreatorBinding(Mode.PROPERTIES,
+				JacksonAutoConfiguration.class);
+	}
+
+	@Test
+	public void customParameterNamesModuleCanBeConfigured() {
+		assertParameterNamesModuleCreatorBinding(Mode.DELEGATING,
+				ParameterNamesModuleConfig.class, JacksonAutoConfiguration.class);
+	}
+
+	private void assertParameterNamesModuleCreatorBinding(Mode expectedMode,
+			Class<?>... configClasses) {
+		this.context.register(configClasses);
+		this.context.refresh();
+		Annotated annotated = mock(Annotated.class);
+		Mode mode = this.context.getBean(ObjectMapper.class).getDeserializationConfig()
+				.getAnnotationIntrospector().findCreatorBinding(annotated);
+		assertThat(mode, is(equalTo(expectedMode)));
+	}
+
 	public static class MyDateFormat extends SimpleDateFormat {
 
 		public MyDateFormat() {
@@ -469,6 +495,16 @@ public class JacksonAutoConfigurationTests {
 
 	}
 
+	@Configuration
+	protected static class ParameterNamesModuleConfig {
+
+		@Bean
+		public ParameterNamesModule parameterNamesModule() {
+			return new ParameterNamesModule(JsonCreator.Mode.DELEGATING);
+		}
+
+	}
+
 	protected static final class Foo {
 
 		private String name;