Optiona Throwable for an explicit recoverer

According to Javadoc of `@Recover`, the `Throwable` first argument is optional.
Before this commit,
```
java.lang.NullPointerException: Cannot invoke "java.lang.Class.isAssignableFrom(java.lang.Class)" because "meta.type" is null
	at org.springframework.retry.annotation.RecoverAnnotationRecoveryHandler.findClosestMatch(RecoverAnnotationRecoveryHandler.java:154)
	at org.springframework.retry.annotation.RecoverAnnotationRecoveryHandler.recover(RecoverAnnotationRecoveryHandler.java:75)
	at org.springframework.retry.interceptor.RetryOperationsInterceptor$ItemRecovererCallback.recover(RetryOperationsInterceptor.java:159)
	at org.springframework.retry.support.RetryTemplate.handleRetryExhausted(RetryTemplate.java:543)
	at org.springframework.retry.support.RetryTemplate.doExecute(RetryTemplate.java:389)
	at org.springframework.retry.support.RetryTemplate.execute(RetryTemplate.java:225)
	at org.springframework.retry.interceptor.RetryOperationsInterceptor.invoke(RetryOperationsInterceptor.java:124)
	at org.springframework.retry.annotation.AnnotationAwareRetryOperationsInterceptor.invoke(AnnotationAwareRetryOperationsInterceptor.java:160)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750)
```
is raised for
```java
@Retryable(retryFor = RuntimeException.class, recover = "recover")
public String service(String param) {
	throw new RuntimeException("Planned");
}

@Recover
public String recover(String param) {
	return param;
}
```

src/main/java/org/springframework/retry/annotation/RecoverAnnotationRecoveryHandler.java

@@ -54,6 +54,7 @@ import org.springframework.util.StringUtils;
  * @author Artem Bilan
  * @author Gianluca Medici
  * @author Lijinliang
+ * @author Yanming Zhou
  */
 public class RecoverAnnotationRecoveryHandler<T> implements MethodInvocationRecoverer<T> {
 
@@ -130,7 +131,7 @@ public class RecoverAnnotationRecoveryHandler<T> implements MethodInvocationReco
 					}
 					else if (distance == min) {
 						boolean parametersMatch = compareParameters(args, meta.getArgCount(),
-								method.getParameterTypes());
+								method.getParameterTypes(), false);
 						if (parametersMatch) {
 							result = method;
 						}
@@ -143,8 +144,8 @@ public class RecoverAnnotationRecoveryHandler<T> implements MethodInvocationReco
 				Method method = entry.getKey();
 				if (method.getName().equals(this.recoverMethodName)) {
 					SimpleMetadata meta = entry.getValue();
-					if (meta.type.isAssignableFrom(cause)
-							&& compareParameters(args, meta.getArgCount(), method.getParameterTypes())) {
+					if ((meta.type == null || meta.type.isAssignableFrom(cause))
+							&& compareParameters(args, meta.getArgCount(), method.getParameterTypes(), true)) {
 						result = method;
 						break;
 					}
@@ -164,8 +165,9 @@ public class RecoverAnnotationRecoveryHandler<T> implements MethodInvocationReco
 		return result;
 	}
 
-	private boolean compareParameters(Object[] args, int argCount, Class<?>[] parameterTypes) {
-		if (argCount == (args.length + 1)) {
+	private boolean compareParameters(Object[] args, int argCount, Class<?>[] parameterTypes,
+			boolean withRecoverMethodName) {
+		if ((withRecoverMethodName && argCount == args.length) || argCount == (args.length + 1)) {
 			int startingIndex = 0;
 			if (parameterTypes.length > 0 && Throwable.class.isAssignableFrom(parameterTypes[0])) {
 				startingIndex = 1;

src/test/java/org/springframework/retry/annotation/EnableRetryTests.java

@@ -141,6 +141,24 @@ public class EnableRetryTests {
 		context.close();
 	}
 
+	@Test
+	public void recoveryWithoutParam() {
+		try (AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(
+				TestConfiguration.class)) {
+			RecoverableService service = context.getBean(RecoverableService.class);
+			assertThat(service.serviceWithoutParam()).isEqualTo("test");
+		}
+	}
+
+	@Test
+	public void recoveryWithParam() {
+		try (AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(
+				TestConfiguration.class)) {
+			RecoverableService service = context.getBean(RecoverableService.class);
+			assertThat(service.serviceWithParam("test")).isEqualTo("test");
+		}
+	}
+
 	@Test
 	public void type() {
 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(TestConfiguration.class);
@@ -637,6 +655,26 @@ public class EnableRetryTests {
 			this.cause = cause;
 		}
 
+		@Retryable(retryFor = RuntimeException.class, recover = "recoverWithoutParam")
+		public String serviceWithoutParam() {
+			throw new RuntimeException("Planned");
+		}
+
+		@Recover
+		public String recoverWithoutParam() {
+			return "test";
+		}
+
+		@Retryable(retryFor = RuntimeException.class, recover = "recoverWithParam")
+		public String serviceWithParam(String param) {
+			throw new RuntimeException("Planned");
+		}
+
+		@Recover
+		public String recoverWithParam(String param) {
+			return param;
+		}
+
 		public Throwable getCause() {
 			return this.cause;
 		}