BeanWrapper auto-grows arrays if necessary

Previously, only indexed access for collections were supported. When
attempting to access the element of an array that had not the requested
size, the call would fail with an IndexOutOfBoundException

This commit harmonize the binding support so that the array is updated
according to the requested index if necessary.

Issue: SPR-12706
(cherry picked from commit aa21339)

spring-beans/src/main/java/org/springframework/beans/BeanWrapperImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 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.
@@ -78,6 +78,7 @@ import org.springframework.util.StringUtils;
  * @author Rod Johnson
  * @author Juergen Hoeller
  * @author Rob Harrop
+ * @author Stephane Nicoll
  * @since 15 April 2001
  * @see #registerCustomEditor
  * @see #setPropertyValues
@@ -978,6 +979,14 @@ public class BeanWrapperImpl extends AbstractPropertyAccessor implements BeanWra
 					}
 					Object convertedValue = convertIfNecessary(propertyName, oldValue, pv.getValue(),
 							requiredType, TypeDescriptor.nested(property(pd), tokens.keys.length));
+					int length = Array.getLength(propValue);
+					if (arrayIndex >= length && arrayIndex < this.autoGrowCollectionLimit) {
+						Class<?> componentType = propValue.getClass().getComponentType();
+						Object newArray = Array.newInstance(componentType, arrayIndex + 1);
+						System.arraycopy(propValue, 0, newArray, 0, length);
+						setPropertyValue(actualName, newArray);
+						propValue = getPropertyValue(actualName);
+					}
 					Array.set(propValue, arrayIndex, convertedValue);
 				}
 				catch (IndexOutOfBoundsException ex) {