Document spring-boot.run.arguments behaviour with multiple arguments

Closes gh-19998

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/AbstractRunMojo.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -145,7 +145,7 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * quotes. When specified, takes precedence over {@link #arguments}.
 	 * @since 2.2.3
 	 */
-	@Parameter(property = "spring-boot.run.arguments", readonly = true)
+	@Parameter(property = "spring-boot.run.arguments")
 	private String commandlineArguments;
 
 	/**

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/site/apt/examples/run-arguments.apt.vm

+ -----
+ Using Application Arguments
+ -----
+ Stephane Nicoll
+ -----
+ 2020-02-11
+ -----
+
+  Application arguments can be specified using <<<arguments>>>. The following sets two
+  arguments: <<<property1>>> and <<<property2=42>>>:
+
+---
+<project>
+  ...
+  <build>
+    <properties>
+      <my.value>42</my.value>
+    </properties>
+    ...
+    <plugins>
+      ...
+      <plugin>
+        <groupId>${project.groupId}</groupId>
+        <artifactId>${project.artifactId}</artifactId>
+        <version>${project.version}</version>
+        <configuration>
+          <arguments>
+            <argument>property1</argument>
+            <argument>property2=${my.value}</argument>
+          </arguments>
+        </configuration>
+        ...
+      </plugin>
+      ...
+    </plugins>
+    ...
+  </build>
+  ...
+</project>
+---
+
+  On the command-line, arguments are separated by a space the same way <<<jvmArguments>>>
+  are. If an argument contains a space, make sure to quote it. In the following example,
+  two arguments are available: <<<property1>>> and <<<property2=Hello World>>>:
+
+---
+mvn spring-boot:run -Dspring-boot.run.arguments="property1 'property2=Hello World'"
+---
+
+
+

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/site/apt/index.apt

@@ -58,6 +58,8 @@ Spring Boot Maven Plugin
 
   * {{{./examples/run-env-variables.html}Using environment variables}}
 
+  * {{{./examples/run-arguments.html}Using application arguments}}
+
   * {{{./examples/it-random-port.html}Random port for integration tests}}
 
   * {{{./examples/it-skip.html}Skip integration tests}}

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/site/site.xml

@@ -14,6 +14,7 @@
 			<item name="Debug the application" href="examples/run-debug.html"/>
 			<item name="Using system properties" href="examples/run-system-properties.html"/>
 			<item name="Using environment variable" href="examples/run-env-variables.html"/>
+			<item name="Using application arguments" href="examples/run-arguments.html"/>
 			<item name="Random port for integration tests" href="examples/it-random-port.html"/>
 			<item name="Skip integration tests" href="examples/it-skip.html"/>
 			<item name="Specify active profiles" href="examples/run-profiles.html"/>