Rename "agent" to "agents" to properly indicate its type

Closes gh-15455

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

@@ -78,10 +78,19 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	 * Path to agent jar. NOTE: the use of agents means that processes will be started by
 	 * forking a new JVM.
 	 * @since 1.0
+	 * @deprecated since version 2.2. Use agents instead.
 	 */
 	@Parameter(property = "spring-boot.run.agent")
 	private File[] agent;
 
+	/**
+	 * Path to agent jars. NOTE: the use of agents means that processes will be started by
+	 * forking a new JVM.
+	 * @since 2.2
+	 */
+	@Parameter(property = "spring-boot.run.agents")
+	private File[] agents;
+
 	/**
 	 * Flag to say that the agent requires -noverify.
 	 * @since 1.0
@@ -218,7 +227,8 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	}
 
 	private boolean hasAgent() {
-		return (this.agent != null && this.agent.length > 0);
+		File[] configuredAgents = determineAgents();
+		return (configuredAgents != null && configuredAgents.length > 0);
 	}
 
 	private boolean hasJvmArgs() {
@@ -360,11 +370,12 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 	}
 
 	private void addAgents(List<String> args) {
-		if (this.agent != null) {
+		File[] configuredAgents = determineAgents();
+		if (configuredAgents != null) {
 			if (getLog().isInfoEnabled()) {
-				getLog().info("Attaching agents: " + Arrays.asList(this.agent));
+				getLog().info("Attaching agents: " + Arrays.asList(configuredAgents));
 			}
-			for (File agent : this.agent) {
+			for (File agent : configuredAgents) {
 				args.add("-javaagent:" + agent);
 			}
 		}
@@ -373,6 +384,11 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 		}
 	}
 
+	@SuppressWarnings("deprecation")
+	private File[] determineAgents() {
+		return (this.agents != null) ? this.agents : this.agent;
+	}
+
 	private void addActiveProfileArgument(RunArguments arguments) {
 		if (this.profiles.length > 0) {
 			StringBuilder arg = new StringBuilder("--spring.profiles.active=");