Make 'org.springframework.boot.ssl` a foundational package

Closes gh-47219

Author: philwebb

config/checkstyle/checkstyle-suppressions.xml

@@ -63,6 +63,7 @@
 	<suppress files="AbstractLaunchScriptIntegrationTests" checks="IllegalImport" />
 	<suppress files="FailureAnalyzers\.java" checks="RedundantModifier" />
 	<suppress files="SpringBootVersion" checks="JavadocPackage" />
+	<suppress files="SpringBootProviderVersion" checks="JavadocPackage" />
 	<suppress files="spring-boot-configuration-processor[\\/]src[\\/]test[\\/]java[\\/]org[\\/]springframework[\\/]boot[\\/]configurationsample[\\/]" checks="SpringDeprecatedCheck"/>
 	<suppress files="ImportTestcontainersTests\.java" checks="InterfaceIsType" />
 	<suppress files="MyContainers\.java" checks="InterfaceIsType" />

config/checkstyle/import-control.xml

@@ -13,6 +13,11 @@
 	<!-- Allow other imports -->
 	<allow pkg=".*" regex="true" />
 
+	<!-- Keep foundation packages away from SpringApplication package -->
+	<subpackage name="ssl">
+		<disallow pkg="org.springframework.boot" exact-match="true"/>
+	</subpackage>
+
 	<!-- Open direct use of micrometer to specific subpackages  -->
 	<subpackage name="metrics">
 		<allow pkg="io.micrometer" />

core/spring-boot/src/main/java/org/springframework/boot/ssl/FixedTrustManagerFactory.java

@@ -24,8 +24,6 @@
 import javax.net.ssl.TrustManagerFactory;
 import javax.net.ssl.TrustManagerFactorySpi;
 
-import org.springframework.boot.SpringBootVersion;
-
 /**
  * {@link TrustManagerFactory} which uses a fixed set of {@link TrustManager
  * TrustManagers}.
@@ -34,9 +32,7 @@
  */
 final class FixedTrustManagerFactory extends TrustManagerFactory {
 
-	private static final Provider PROVIDER = new Provider("FixedTrustManagerFactory", SpringBootVersion.getVersion(),
-			"") {
-	};
+	private static final Provider PROVIDER = new FixedTrustManagerFactoryProvider();
 
 	private FixedTrustManagerFactory(FixedTrustManagersSpi spi, String algorithm) {
 		super(spi, PROVIDER, algorithm);
@@ -70,4 +66,12 @@ protected TrustManager[] engineGetTrustManagers() {
 
 	}
 
+	private static class FixedTrustManagerFactoryProvider extends Provider {
+
+		FixedTrustManagerFactoryProvider() {
+			super("FixedTrustManagerFactory", SpringBootProviderVersion.get(), "");
+		}
+
+	}
+
 }

core/spring-boot/src/main/javaTemplates/org/springframework/boot/ssl/SpringBootProviderVersion.java

@@ -0,0 +1,37 @@
+/*
+ * 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.ssl;
+
+/**
+ * Exposes the Spring Boot version for SSL Provider use.
+ *
+ * @author Phillip Webb
+ */
+final class SpringBootProviderVersion {
+
+	private SpringBootProviderVersion() {
+	}
+
+	/**
+	 * Return the full version string of the present Spring Boot codebase.
+	 * @return the version of Spring Boot
+	 */
+	static String get() {
+		return "${springBootVersion}";
+	}
+
+}