New Feature - PlantUML visualization

spring-statemachine-uml/spring-statemachine-uml.gradle

@@ -27,11 +27,24 @@ dependencies {
 	api 'org.eclipse.emf:org.eclipse.emf.ecore.xmi'
 	api 'org.eclipse.emf:org.eclipse.emf.ecore'
 	api 'org.eclipse.emf:org.eclipse.emf.common'
+
+	implementation 'org.apache.commons:commons-lang3:3.12.0'
+	implementation'net.sourceforge.plantuml:plantuml-lgpl:1.2023.13'
+	implementation 'jakarta.validation:jakarta.validation-api:3.1.0'
+
 	testImplementation(testFixtures(project(":spring-statemachine-core")))
 	testImplementation 'org.assertj:assertj-core'
 	testImplementation 'io.projectreactor:reactor-test'
 	testImplementation 'org.springframework:spring-test'
 	testImplementation 'org.junit.jupiter:junit-jupiter-api'
 	testImplementation 'org.junit.jupiter:junit-jupiter-engine'
+	testImplementation 'org.junit.jupiter:junit-jupiter-params'
 	testImplementation 'org.awaitility:awaitility'
+
+	// lombok
+	implementation 'org.projectlombok:lombok:1.18.32'
+	compileOnly 'org.projectlombok:lombok:1.18.32'
+	annotationProcessor 'org.projectlombok:lombok:1.18.32'
+	testImplementation 'org.projectlombok:lombok:1.18.32'
+	testAnnotationProcessor 'org.projectlombok:lombok:1.18.32'
 }

spring-statemachine-uml/src/main/java/org/springframework/statemachine/plantuml/ContextTransition.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2002-2024 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.statemachine.plantuml;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import org.springframework.lang.Nullable;
+import org.springframework.statemachine.StateContext;
+
+@AllArgsConstructor
+@Getter
+public class ContextTransition<S, E> {
+	final S source;
+	final E event;
+	final S target;
+
+	public static <S, E> ContextTransition<S, E> of(@Nullable StateContext<S, E> stateContext) {
+		if (stateContext != null) {
+			return new ContextTransition<>(
+					stateContext.getSource() != null
+							? stateContext.getSource().getId()
+							: null,
+					stateContext.getEvent(),
+					stateContext.getTarget() != null
+							? stateContext.getTarget().getId()
+							: null
+			);
+		}
+		return null;
+	}
+}