Make Resource Server auto-config conditional on JwtDecoder class

Fixes gh-15372

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/oauth2/resource/reactive/ReactiveOAuth2ResourceServerAutoConfiguration.java

@@ -25,6 +25,7 @@ import org.springframework.boot.context.properties.EnableConfigurationProperties
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.security.config.annotation.web.reactive.EnableWebFluxSecurity;
+import org.springframework.security.oauth2.jwt.JwtDecoder;
 import org.springframework.security.oauth2.server.resource.BearerTokenAuthenticationToken;
 
 /**
@@ -37,7 +38,8 @@ import org.springframework.security.oauth2.server.resource.BearerTokenAuthentica
 @Configuration
 @AutoConfigureBefore(ReactiveSecurityAutoConfiguration.class)
 @EnableConfigurationProperties(OAuth2ResourceServerProperties.class)
-@ConditionalOnClass({ EnableWebFluxSecurity.class, BearerTokenAuthenticationToken.class })
+@ConditionalOnClass({ EnableWebFluxSecurity.class, BearerTokenAuthenticationToken.class,
+		JwtDecoder.class })
 @ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.REACTIVE)
 @Import({ ReactiveOAuth2ResourceServerJwkConfiguration.class,
 		ReactiveOAuth2ResourceServerWebSecurityConfiguration.class })

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/oauth2/resource/servlet/OAuth2ResourceServerAutoConfiguration.java

@@ -24,6 +24,7 @@ import org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfi
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
+import org.springframework.security.oauth2.jwt.JwtDecoder;
 import org.springframework.security.oauth2.server.resource.authentication.JwtAuthenticationToken;
 
 /**
@@ -35,7 +36,7 @@ import org.springframework.security.oauth2.server.resource.authentication.JwtAut
 @Configuration
 @AutoConfigureBefore(SecurityAutoConfiguration.class)
 @EnableConfigurationProperties(OAuth2ResourceServerProperties.class)
-@ConditionalOnClass(JwtAuthenticationToken.class)
+@ConditionalOnClass({ JwtAuthenticationToken.class, JwtDecoder.class })
 @ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.SERVLET)
 @Import({ OAuth2ResourceServerJwtConfiguration.class,
 		OAuth2ResourceServerWebSecurityConfiguration.class })

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/oauth2/resource/reactive/ReactiveOAuth2ResourceServerAutoConfigurationTests.java

@@ -154,6 +154,16 @@ public class ReactiveOAuth2ResourceServerAutoConfigurationTests {
 						.doesNotHaveBean(BeanIds.SPRING_SECURITY_FILTER_CHAIN));
 	}
 
+	@Test
+	public void autoConfigurationShouldBeConditionalOnReactiveJwtDecoderClass() {
+		this.contextRunner.withPropertyValues(
+				"spring.security.oauth2.resourceserver.jwt.jwk-set-uri=http://jwk-set-uri.com")
+				.withUserConfiguration(JwtDecoderConfig.class)
+				.withClassLoader(new FilteredClassLoader(ReactiveJwtDecoder.class))
+				.run((context) -> assertThat(context)
+						.doesNotHaveBean(BeanIds.SPRING_SECURITY_FILTER_CHAIN));
+	}
+
 	@Test
 	public void autoConfigurationWhenSecurityWebFilterChainConfigPresentShouldNotAddOne() {
 		this.contextRunner.withPropertyValues(

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/oauth2/resource/servlet/OAuth2ResourceServerAutoConfigurationTests.java

@@ -149,6 +149,15 @@ public class OAuth2ResourceServerAutoConfigurationTests {
 				.run((context) -> assertThat(getBearerTokenFilter(context)).isNull());
 	}
 
+	@Test
+	public void autoConfigurationShouldBeConditionalOnJwtDecoderClass() {
+		this.contextRunner.withPropertyValues(
+				"spring.security.oauth2.resourceserver.jwt.jwk-set-uri=http://jwk-set-uri.com")
+				.withUserConfiguration(JwtDecoderConfig.class)
+				.withClassLoader(new FilteredClassLoader(JwtDecoder.class))
+				.run((context) -> assertThat(getBearerTokenFilter(context)).isNull());
+	}
+
 	@SuppressWarnings("unchecked")
 	private Filter getBearerTokenFilter(AssertableWebApplicationContext context) {
 		FilterChainProxy filterChain = (FilterChainProxy) context