Merge pull request #44850 from dobrosi

* pr/44850:
  Polish "Add support for configuring LDAP's referral property"
  Add support for configuring LDAP's referral property

Closes gh-44850

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/ldap/LdapAutoConfiguration.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.autoconfigure.ldap;
 
 import java.util.Collections;
+import java.util.Locale;
 
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.AutoConfiguration;
@@ -67,6 +68,9 @@ public class LdapAutoConfiguration {
 		propertyMapper.from(connectionDetails.getUsername()).to(source::setUserDn);
 		propertyMapper.from(connectionDetails.getPassword()).to(source::setPassword);
 		propertyMapper.from(properties.getAnonymousReadOnly()).to(source::setAnonymousReadOnly);
+		propertyMapper.from(properties.getReferral())
+			.as(((referral) -> referral.name().toLowerCase(Locale.ROOT)))
+			.to(source::setReferral);
 		propertyMapper.from(connectionDetails.getBase()).to(source::setBase);
 		propertyMapper.from(connectionDetails.getUrls()).to(source::setUrls);
 		propertyMapper.from(properties.getBaseEnvironment())

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/ldap/LdapProperties.java

@@ -21,6 +21,7 @@ import java.util.Map;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.core.env.Environment;
+import org.springframework.ldap.ReferralException;
 import org.springframework.ldap.core.LdapTemplate;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
@@ -62,6 +63,12 @@ public class LdapProperties {
 	 */
 	private Boolean anonymousReadOnly;
 
+	/**
+	 * Specify how referrals encountered by the service provider are to be processed. If
+	 * not specified, the default is determined by the provider.
+	 */
+	private Referral referral;
+
 	/**
 	 * LDAP specification settings.
 	 */
@@ -109,6 +116,14 @@ public class LdapProperties {
 		this.anonymousReadOnly = anonymousReadOnly;
 	}
 
+	public Referral getReferral() {
+		return this.referral;
+	}
+
+	public void setReferral(Referral referral) {
+		this.referral = referral;
+	}
+
 	public Map<String, String> getBaseEnvironment() {
 		return this.baseEnvironment;
 	}
@@ -182,4 +197,26 @@ public class LdapProperties {
 
 	}
 
+	/**
+	 * Define the methods to handle referrals.
+	 */
+	public enum Referral {
+
+		/**
+		 * Follow referrals automatically.
+		 */
+		FOLLOW,
+
+		/**
+		 * Ignore referrals.
+		 */
+		IGNORE,
+
+		/**
+		 * Throw {@link ReferralException} when a referral is encountered.
+		 */
+		THROW
+
+	}
+
 }

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/ldap/LdapAutoConfigurationTests.java

@@ -88,6 +88,14 @@ class LdapAutoConfigurationTests {
 		});
 	}
 
+	@Test
+	void contextSourceWithReferral() {
+		this.contextRunner.withPropertyValues("spring.ldap.referral:ignore").run((context) -> {
+			LdapContextSource contextSource = context.getBean(LdapContextSource.class);
+			assertThat(contextSource).hasFieldOrPropertyWithValue("referral", "ignore");
+		});
+	}
+
 	@Test
 	void contextSourceWithExtraCustomization() {
 		this.contextRunner