HandlerMethodParameter defensively handles interface annotation arrays

Issue: SPR-17629

spring-web/src/main/java/org/springframework/web/method/HandlerMethod.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -481,23 +481,26 @@ public class HandlerMethod {
 			if (anns == null) {
 				anns = super.getParameterAnnotations();
 				for (Annotation[][] ifcAnns : getInterfaceParameterAnnotations()) {
-					Annotation[] paramAnns = ifcAnns[getParameterIndex()];
-					if (paramAnns.length > 0) {
-						List<Annotation> merged = new ArrayList<>(anns.length + paramAnns.length);
-						merged.addAll(Arrays.asList(anns));
-						for (Annotation paramAnn : paramAnns) {
-							boolean existingType = false;
-							for (Annotation ann : anns) {
-								if (ann.annotationType() == paramAnn.annotationType()) {
-									existingType = true;
-									break;
+					int index = getParameterIndex();
+					if (index < ifcAnns.length) {
+						Annotation[] paramAnns = ifcAnns[index];
+						if (paramAnns.length > 0) {
+							List<Annotation> merged = new ArrayList<>(anns.length + paramAnns.length);
+							merged.addAll(Arrays.asList(anns));
+							for (Annotation paramAnn : paramAnns) {
+								boolean existingType = false;
+								for (Annotation ann : anns) {
+									if (ann.annotationType() == paramAnn.annotationType()) {
+										existingType = true;
+										break;
+									}
+								}
+								if (!existingType) {
+									merged.add(adaptAnnotation(paramAnn));
 								}
 							}
-							if (!existingType) {
-								merged.add(adaptAnnotation(paramAnn));
-							}
+							anns = merged.toArray(new Annotation[0]);
 						}
-						anns = merged.toArray(new Annotation[0]);
 					}
 				}
 				this.combinedAnnotations = anns;