Fix jdk8 javadoc build

build.gradle

@@ -295,12 +295,8 @@ configure(rootProject) {
 		from('src/dist') {
 			include 'changelog.txt'
 		}
-		// disable api for jdk8 because we have
-		// some trouble with javadocs
-		if (!JavaVersion.current().isJava8Compatible()) {
-			from (api) {
-				into 'api'
-			}
+		from (api) {
+			into 'api'
 		}
 		from (reference) {
 			into 'reference'

spring-statemachine-core/src/main/java/org/springframework/statemachine/ExtendedState.java

@@ -37,6 +37,7 @@ public interface ExtendedState {
 	/**
 	 * Gets a variable which is automatically casted into a type.
 	 *
+	 * @param <T> the return type
 	 * @param key the variable key
 	 * @param type the variable type
 	 * @return the variable

spring-statemachine-core/src/main/java/org/springframework/statemachine/config/configurers/ConfigurationConfigurer.java

@@ -44,7 +44,7 @@ public interface ConfigurationConfigurer<S, E> extends
 	/**
 	 * Specify a {@link TaskExecutor}.
 	 *
-	 * @param beanFactory the bean factory
+	 * @param taskExecutor the task executor
 	 * @return configurer for chaining
 	 */
 	ConfigurationConfigurer<S, E> taskExecutor(TaskExecutor taskExecutor);
@@ -52,7 +52,7 @@ public interface ConfigurationConfigurer<S, E> extends
 	/**
 	 * Specify a {@link TaskScheduler}.
 	 *
-	 * @param beanFactory the bean factory
+	 * @param taskScheduler the task scheduler
 	 * @return configurer for chaining
 	 */
 	ConfigurationConfigurer<S, E> taskScheduler(TaskScheduler taskScheduler);

spring-statemachine-core/src/main/java/org/springframework/statemachine/event/OnStateChangedEvent.java

@@ -33,6 +33,8 @@ public class OnStateChangedEvent extends StateMachineEvent {
 	 * Instantiates a new on state changed event.
 	 *
 	 * @param source the component that published the event (never {@code null})
+	 * @param sourceState the source state
+	 * @param targetState the target state
 	 */
 	public OnStateChangedEvent(Object source, State<?, ?> sourceState, State<?, ?> targetState) {
 		super(source);

spring-statemachine-core/src/main/java/org/springframework/statemachine/support/AbstractStateMachine.java

@@ -143,6 +143,7 @@ public abstract class AbstractStateMachine<S, E> extends StateMachineObjectSuppo
 	 * @param states the states of this machine
 	 * @param transitions the transitions of this machine
 	 * @param initialState the initial state of this machine
+	 * @param initialTransition the initial transition
 	 * @param initialEvent the initial event of this machine
 	 * @param extendedState the extended state of this machine
 	 */

spring-statemachine-core/src/main/java/org/springframework/statemachine/support/DefaultStateMachineExecutor.java

@@ -99,6 +99,8 @@ public class DefaultStateMachineExecutor<S, E> extends LifecycleObjectSupport im
 	 * @param transitions the transitions
 	 * @param triggerToTransitionMap the trigger to transition map
 	 * @param triggerlessTransitions the triggerless transitions
+	 * @param initialTransition the initial transition
+	 * @param initialEvent the initial event
 	 */
 	public DefaultStateMachineExecutor(StateMachine<S, E> stateMachine, StateMachine<S, E> relayStateMachine,
 			ExtendedState extendedState, Collection<Transition<S, E>> transitions, Map<Trigger<S, E>, Transition<S, E>> triggerToTransitionMap,

spring-statemachine-core/src/main/java/org/springframework/statemachine/support/StateMachineUtils.java

@@ -32,6 +32,8 @@ public abstract class StateMachineUtils {
 	/**
 	 * Checks if right hand side is a substate of a left hand side.
 	 *
+	 * @param <S> the type of state
+	 * @param <E> the type of event
 	 * @param left the super state
 	 * @param right the sub state
 	 * @return if sub is child of super

spring-statemachine-recipes/src/main/java/org/springframework/statemachine/recipes/persist/PersistStateMachineHandler.java

@@ -94,7 +94,7 @@ public class PersistStateMachineHandler extends LifecycleObjectSupport {
 	 * The class that is interested in processing a persistStateChange
 	 * event implements this interface, and the object created
 	 * with that class is registered with a component using the
-	 * component's <code>addPersistStateChangeListener<code> method. When
+	 * component's <code>addPersistStateChangeListener</code> method. When
 	 * the persistStateChange event occurs, that object's appropriate
 	 * method is invoked.
 	 */

spring-statemachine-test/src/main/java/org/springframework/statemachine/test/StateMachineTestPlanBuilder.java

@@ -41,6 +41,8 @@ public class StateMachineTestPlanBuilder<S, E> {
 	/**
 	 * Gets a new instance of this builder.
 	 *
+	 * @param <S> the type of state
+	 * @param <E> the type of event
 	 * @return the state machine test plan builder
 	 */
 	public static <S, E> StateMachineTestPlanBuilder<S, E> builder() {