Do not attempt to add Jaxb customization if Jaxb is not present

See gh-16268

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jersey/JerseyAutoConfiguration.java

@@ -25,6 +25,7 @@ import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRegistration;
 import javax.ws.rs.ext.ContextResolver;
+import javax.xml.bind.annotation.XmlElement;
 
 import com.fasterxml.jackson.databind.AnnotationIntrospector;
 import com.fasterxml.jackson.databind.ObjectMapper;
@@ -39,6 +40,7 @@ import org.glassfish.jersey.servlet.ServletContainer;
 import org.glassfish.jersey.servlet.ServletProperties;
 
 import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.AutoConfigureBefore;
 import org.springframework.boot.autoconfigure.AutoConfigureOrder;
@@ -201,17 +203,14 @@ public class JerseyAutoConfiguration implements ServletContextAware {
 
 	}
 
+	@Configuration
 	@ConditionalOnClass(JacksonFeature.class)
 	@ConditionalOnSingleCandidate(ObjectMapper.class)
-	@Configuration
 	static class JacksonResourceConfigCustomizer {
 
-		private static final String JAXB_ANNOTATION_INTROSPECTOR_CLASS_NAME = "com.fasterxml.jackson.module.jaxb.JaxbAnnotationIntrospector";
-
 		@Bean
 		public ResourceConfigCustomizer resourceConfigCustomizer(
 				final ObjectMapper objectMapper) {
-			addJaxbAnnotationIntrospectorIfPresent(objectMapper);
 			return (ResourceConfig config) -> {
 				config.register(JacksonFeature.class);
 				config.register(new ObjectMapperContextResolver(objectMapper),
@@ -219,16 +218,12 @@ public class JerseyAutoConfiguration implements ServletContextAware {
 			};
 		}
 
-		private void addJaxbAnnotationIntrospectorIfPresent(ObjectMapper objectMapper) {
-			if (ClassUtils.isPresent(JAXB_ANNOTATION_INTROSPECTOR_CLASS_NAME,
-					getClass().getClassLoader())) {
-				new ObjectMapperCustomizer().addJaxbAnnotationIntrospector(objectMapper);
-			}
-		}
-
-		private static final class ObjectMapperCustomizer {
+		@Configuration
+		@ConditionalOnClass({ JaxbAnnotationIntrospector.class, XmlElement.class })
+		static class JaxbObjectMapperCustomizer {
 
-			private void addJaxbAnnotationIntrospector(ObjectMapper objectMapper) {
+			@Autowired
+			public void addJaxbAnnotationIntrospector(ObjectMapper objectMapper) {
 				JaxbAnnotationIntrospector jaxbAnnotationIntrospector = new JaxbAnnotationIntrospector(
 						objectMapper.getTypeFactory());
 				objectMapper.setAnnotationIntrospectors(

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jersey/JerseyAutoConfigurationTests.java

@@ -16,12 +16,16 @@
 
 package org.springframework.boot.autoconfigure.jersey;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.module.jaxb.JaxbAnnotationIntrospector;
 import org.glassfish.jersey.server.ResourceConfig;
 import org.junit.Test;
 
 import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
 import org.springframework.boot.autoconfigure.logging.ConditionEvaluationReportLoggingListener;
 import org.springframework.boot.logging.LogLevel;
+import org.springframework.boot.test.context.FilteredClassLoader;
 import org.springframework.boot.test.context.runner.WebApplicationContextRunner;
 import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.context.annotation.Bean;
@@ -72,6 +76,48 @@ public class JerseyAutoConfigurationTests {
 				});
 	}
 
+	@Test
+	public void whenJaxbIsAvailableTheObjectMapperIsCustomizedWithAnAnnotationIntrospector() {
+		this.contextRunner
+				.withConfiguration(AutoConfigurations.of(JacksonAutoConfiguration.class))
+				.run((context) -> {
+					ObjectMapper objectMapper = context.getBean(ObjectMapper.class);
+					assertThat(objectMapper.getSerializationConfig()
+							.getAnnotationIntrospector().allIntrospectors().stream()
+							.filter(JaxbAnnotationIntrospector.class::isInstance))
+									.hasSize(1);
+				});
+	}
+
+	@Test
+	public void whenJaxbIsNotAvailableTheObjectMapperCustomizationBacksOff() {
+		this.contextRunner
+				.withConfiguration(AutoConfigurations.of(JacksonAutoConfiguration.class))
+				.withClassLoader(new FilteredClassLoader("javax.xml.bind.annotation"))
+				.run((context) -> {
+					ObjectMapper objectMapper = context.getBean(ObjectMapper.class);
+					assertThat(objectMapper.getSerializationConfig()
+							.getAnnotationIntrospector().allIntrospectors().stream()
+							.filter(JaxbAnnotationIntrospector.class::isInstance))
+									.isEmpty();
+				});
+	}
+
+	@Test
+	public void whenJacksonJaxbModuleIsNotAvailableTheObjectMapperCustomizationBacksOff() {
+		this.contextRunner
+				.withConfiguration(AutoConfigurations.of(JacksonAutoConfiguration.class))
+				.withClassLoader(
+						new FilteredClassLoader(JaxbAnnotationIntrospector.class))
+				.run((context) -> {
+					ObjectMapper objectMapper = context.getBean(ObjectMapper.class);
+					assertThat(objectMapper.getSerializationConfig()
+							.getAnnotationIntrospector().allIntrospectors().stream()
+							.filter(JaxbAnnotationIntrospector.class::isInstance))
+									.isEmpty();
+				});
+	}
+
 	@Configuration
 	static class ResourceConfigConfiguration {