Use app…DefaultJvmArgs as convention for start script's defaultJvmOpts

Closes gh-12631

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/asciidoc/reacting.adoc

@@ -70,8 +70,10 @@ applied to a project, the Spring Boot plugin will automatically import the
 When Gradle's {application-plugin}[`application` plugin] is applied to a project, the
 Spring Boot plugin:
 
-1. Creates a `CreateStartScripts` task named `bootStartScripts` that will creates scripts
-   that launch the artifact in the `bootArchives` configuration using `java -jar`.
+1. Creates a `CreateStartScripts` task named `bootStartScripts` that will create scripts
+   that launch the artifact in the `bootArchives` configuration using `java -jar`. The
+   task is configured to use the `applicationDefaultJvmArgs` property as a convention
+   for its `defaultJvmOpts` property.
 2. Creates a new distribution named `boot` and configures it to contain the artifact in
    the `bootArchives` configuration in its `lib` directory and the start scripts in its
    `bin` directory.

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/plugin/ApplicationPluginAction.java

@@ -77,6 +77,8 @@ final class ApplicationPluginAction implements PluginApplicationAction {
 				() -> new File(project.getBuildDir(), "bootScripts"));
 		bootStartScripts.getConventionMapping().map("applicationName",
 				applicationConvention::getApplicationName);
+		bootStartScripts.getConventionMapping().map("defaultJvmOpts",
+				applicationConvention::getApplicationDefaultJvmArgs);
 		CopySpec binCopySpec = project.copySpec().into("bin").from(bootStartScripts);
 		binCopySpec.setFileMode(0x755);
 		distribution.getContents().with(binCopySpec);