Remove isImmutable and getPrefix from OriginLookup

Drop `isImmutable` and `getPrefix` from `OriginLookup` since
they're not really Origin concerns. Now that `env` is a
foundational layer we can add a dedicated `PropertySourceInfo`
interface and add that to the `o.s.b.env` package without
creating a package tangle.

Closes gh-45547

Author: philwebb

config/checkstyle/import-control.xml

@@ -45,6 +45,9 @@
 	<subpackage name="ssl">
 		<disallow pkg="org.springframework.boot" exact-match="true"/>
 	</subpackage>
+	<subpackage name="origin">
+		<disallow pkg="org.springframework.boot" exact-match="true"/>
+	</subpackage>
 	<subpackage name="util">
 		<disallow pkg="org.springframework.boot" exact-match="true"/>
 	</subpackage>

core/spring-boot/src/main/java/org/springframework/boot/ApplicationInfoPropertySource.java

@@ -21,8 +21,7 @@
 
 import org.jspecify.annotations.Nullable;
 
-import org.springframework.boot.origin.Origin;
-import org.springframework.boot.origin.OriginLookup;
+import org.springframework.boot.env.PropertySourceInfo;
 import org.springframework.boot.system.ApplicationPid;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.MapPropertySource;
@@ -36,7 +35,7 @@
  *
  * @author Moritz Halbritter
  */
-class ApplicationInfoPropertySource extends MapPropertySource implements OriginLookup<String> {
+class ApplicationInfoPropertySource extends MapPropertySource implements PropertySourceInfo {
 
 	static final String NAME = "applicationInfo";
 
@@ -48,11 +47,6 @@ class ApplicationInfoPropertySource extends MapPropertySource implements OriginL
 		super(NAME, getProperties(applicationVersion));
 	}
 
-	@Override
-	public @Nullable Origin getOrigin(String key) {
-		return null;
-	}
-
 	@Override
 	public boolean isImmutable() {
 		return true;

core/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigDataEnvironmentContributor.java

@@ -31,7 +31,7 @@
 import org.springframework.boot.context.properties.bind.Binder;
 import org.springframework.boot.context.properties.bind.PlaceholdersResolver;
 import org.springframework.boot.context.properties.source.ConfigurationPropertySource;
-import org.springframework.boot.origin.OriginLookup;
+import org.springframework.boot.env.PropertySourceInfo;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.env.Environment;
 import org.springframework.core.env.PropertySource;
@@ -454,8 +454,8 @@ static ConfigDataEnvironmentContributor ofUnboundImport(@Nullable ConfigDataLoca
 	private static @Nullable ConfigurationPropertySource asConfigurationPropertySource(
 			PropertySource<?> propertySource) {
 		ConfigurationPropertySource configurationPropertySource = ConfigurationPropertySource.from(propertySource);
-		if (configurationPropertySource != null && propertySource instanceof OriginLookup<?> originLookup) {
-			configurationPropertySource = configurationPropertySource.withPrefix(originLookup.getPrefix());
+		if (configurationPropertySource != null && propertySource instanceof PropertySourceInfo propertySourceInfo) {
+			configurationPropertySource = configurationPropertySource.withPrefix(propertySourceInfo.getPrefix());
 		}
 		return configurationPropertySource;
 	}

core/spring-boot/src/main/java/org/springframework/boot/context/properties/source/SpringConfigurationPropertySources.java

@@ -25,7 +25,7 @@
 
 import org.jspecify.annotations.Nullable;
 
-import org.springframework.boot.origin.OriginLookup;
+import org.springframework.boot.env.PropertySourceInfo;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.MutablePropertySources;
 import org.springframework.core.env.PropertySource;
@@ -69,8 +69,8 @@ private ConfigurationPropertySource adapt(PropertySource<?> source) {
 			return result;
 		}
 		result = SpringConfigurationPropertySource.from(source);
-		if (source instanceof OriginLookup<?> originLookup) {
-			result = result.withPrefix(originLookup.getPrefix());
+		if (source instanceof PropertySourceInfo propertySourceInfo) {
+			result = result.withPrefix(propertySourceInfo.getPrefix());
 		}
 		this.cache.put(source, result);
 		return result;

core/spring-boot/src/main/java/org/springframework/boot/context/properties/source/SpringIterableConfigurationPropertySource.java

@@ -32,8 +32,8 @@
 
 import org.jspecify.annotations.Nullable;
 
+import org.springframework.boot.env.PropertySourceInfo;
 import org.springframework.boot.origin.Origin;
-import org.springframework.boot.origin.OriginLookup;
 import org.springframework.boot.origin.PropertySourceOrigin;
 import org.springframework.core.env.EnumerablePropertySource;
 import org.springframework.core.env.MapPropertySource;
@@ -202,8 +202,8 @@ private Cache updateCache(Cache cache) {
 
 	boolean isImmutablePropertySource() {
 		EnumerablePropertySource<?> source = getPropertySource();
-		if (source instanceof OriginLookup<?> originLookup) {
-			return originLookup.isImmutable();
+		if (source instanceof PropertySourceInfo propertySourceInfo) {
+			return propertySourceInfo.isImmutable();
 		}
 		if (StandardEnvironment.SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME.equals(source.getName())) {
 			return source.getSource() == System.getenv();

core/spring-boot/src/main/java/org/springframework/boot/env/ConfigTreePropertySource.java

@@ -76,7 +76,8 @@
  * @author Phillip Webb
  * @since 2.4.0
  */
-public class ConfigTreePropertySource extends EnumerablePropertySource<Path> implements OriginLookup<String> {
+public class ConfigTreePropertySource extends EnumerablePropertySource<Path>
+		implements PropertySourceInfo, OriginLookup<String> {
 
 	private static final int MAX_DEPTH = 100;
 

core/spring-boot/src/main/java/org/springframework/boot/env/OriginTrackedMapPropertySource.java

@@ -34,7 +34,8 @@
  * @since 2.0.0
  * @see OriginTrackedValue
  */
-public final class OriginTrackedMapPropertySource extends MapPropertySource implements OriginLookup<String> {
+public final class OriginTrackedMapPropertySource extends MapPropertySource
+		implements PropertySourceInfo, OriginLookup<String> {
 
 	private final boolean immutable;
 

core/spring-boot/src/main/java/org/springframework/boot/env/PropertySourceInfo.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2012-present 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
+ *
+ *      https://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.env;
+
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.core.env.PropertySource;
+
+/**
+ * Interface that can be optionally implemented by a {@link PropertySource} to provide
+ * additional information.
+ *
+ * @author Phillip Webb
+ * @since 4.0.0
+ */
+public interface PropertySourceInfo {
+
+	/**
+	 * Return {@code true} if this lookup is immutable and has contents that will never
+	 * change.
+	 * @return if the lookup is immutable
+	 */
+	default boolean isImmutable() {
+		return false;
+	}
+
+	/**
+	 * Return the implicit prefix that is applied when performing a lookup or {@code null}
+	 * if no prefix is used. Prefixes can be used to disambiguate keys that would
+	 * otherwise clash. For example, if multiple applications are running on the same
+	 * machine a different prefix can be set on each application to ensure that different
+	 * environment variables are used.
+	 * @return the prefix applied by the lookup class or {@code null}.
+	 */
+	default @Nullable String getPrefix() {
+		return null;
+	}
+
+}

core/spring-boot/src/main/java/org/springframework/boot/origin/OriginLookup.java

@@ -37,29 +37,6 @@ public interface OriginLookup<K> {
 	 */
 	@Nullable Origin getOrigin(K key);
 
-	/**
-	 * Return {@code true} if this lookup is immutable and has contents that will never
-	 * change.
-	 * @return if the lookup is immutable
-	 * @since 2.2.0
-	 */
-	default boolean isImmutable() {
-		return false;
-	}
-
-	/**
-	 * Return the implicit prefix that is applied when performing a lookup or {@code null}
-	 * if no prefix is used. Prefixes can be used to disambiguate keys that would
-	 * otherwise clash. For example, if multiple applications are running on the same
-	 * machine a different prefix can be set on each application to ensure that different
-	 * environment variables are used.
-	 * @return the prefix applied by the lookup class or {@code null}.
-	 * @since 2.5.0
-	 */
-	default @Nullable String getPrefix() {
-		return null;
-	}
-
 	/**
 	 * Attempt to look up the origin from the given source. If the source is not a
 	 * {@link OriginLookup} or if an exception occurs during lookup then {@code null} is

core/spring-boot/src/main/java/org/springframework/boot/support/SystemEnvironmentPropertySourceEnvironmentPostProcessor.java

@@ -22,6 +22,7 @@
 
 import org.springframework.boot.EnvironmentPostProcessor;
 import org.springframework.boot.SpringApplication;
+import org.springframework.boot.env.PropertySourceInfo;
 import org.springframework.boot.origin.Origin;
 import org.springframework.boot.origin.OriginLookup;
 import org.springframework.boot.origin.SystemEnvironmentOrigin;
@@ -81,7 +82,7 @@ public void setOrder(int order) {
 	 * {@link SystemEnvironmentPropertySource} that also tracks {@link Origin}.
 	 */
 	protected static class OriginAwareSystemEnvironmentPropertySource extends SystemEnvironmentPropertySource
-			implements OriginLookup<String> {
+			implements PropertySourceInfo, OriginLookup<String> {
 
 		private final @Nullable String prefix;