INIT INFO Required Start/Stop as embedded launch script properties

Expose the Required-Start and Require-Stop lines in the launch script
INIT INFO section as customizable embedded launch script properties.

This way one can express dependencies fron other init services by simply
changing the configuration in the build script.

Closes gh-7555

spring-boot-docs/src/main/asciidoc/deployment.adoc

@@ -598,6 +598,12 @@ The following property substitutions are supported with the default script:
 |The `Provides` section of "`INIT INFO`". Defaults to `spring-boot-application` for Gradle
  and to `${project.artifactId}` for Maven.
 
+|`initInfoRequiredStart`
+|The `Required-Start` section of "`INIT INFO`". Defaults to `$remote_fs $syslog $network`.
+
+|`initInfoRequiredStop`
+|The `Required-Stop` section of "`INIT INFO`". Defaults to `$remote_fs $syslog $network`.
+
 |`initInfoShortDescription`
 |The `Short-Description` section of "`INIT INFO`". Defaults to `Spring Boot Application`
 for Gradle and to `${project.name}` for Maven.

spring-boot-tools/spring-boot-loader-tools/src/main/resources/org/springframework/boot/loader/tools/launch.script

@@ -11,8 +11,8 @@
 
 ### BEGIN INIT INFO
 # Provides:          {{initInfoProvides:spring-boot-application}}
-# Required-Start:    $remote_fs $syslog $network
-# Required-Stop:     $remote_fs $syslog $network
+# Required-Start:    {{initInfoRequiredStart:$remote_fs $syslog $network}}
+# Required-Stop:     {{initInfoRequiredStop:$remote_fs $syslog $network}}
 # Default-Start:     2 3 4 5
 # Default-Stop:      0 1 6
 # Short-Description: {{initInfoShortDescription:Spring Boot Application}}

spring-boot-tools/spring-boot-loader-tools/src/test/java/org/springframework/boot/loader/tools/DefaultLaunchScriptTests.java

@@ -61,6 +61,16 @@ public class DefaultLaunchScriptTests {
 		assertThatPlaceholderCanBeReplaced("initInfoProvides");
 	}
 
+	@Test
+	public void initInfoRequiredStartCanBeReplaced() throws Exception {
+		assertThatPlaceholderCanBeReplaced("initInfoRequiredStart");
+	}
+
+	@Test
+	public void initInfoRequiredStopCanBeReplaced() throws Exception {
+		assertThatPlaceholderCanBeReplaced("initInfoRequiredStop");
+	}
+
 	@Test
 	public void initInfoShortDescriptionCanBeReplaced() throws Exception {
 		assertThatPlaceholderCanBeReplaced("initInfoShortDescription");