Minor fix in FlowPartialViewContext

The fix ensures that getRenderIds returns a mutable collection as
stated in the contract for the method in PartialViewContext.

Issues: SWF-1480

spring-faces/src/main/java/org/springframework/faces/webflow/FlowPartialViewContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2004-2011 the original author or authors.
+ * Copyright 2004-2012 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.
@@ -15,6 +15,7 @@
  */
 package org.springframework.faces.webflow;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 
@@ -55,7 +56,7 @@ public class FlowPartialViewContext extends PartialViewContextWrapper {
 			RequestContext requestContext = RequestContextHolder.getRequestContext();
 			String[] fragmentIds = (String[]) requestContext.getFlashScope().get(View.RENDER_FRAGMENTS_ATTRIBUTE);
 			if (fragmentIds != null && fragmentIds.length > 0) {
-				return Arrays.asList(fragmentIds);
+				return new ArrayList<String>(Arrays.asList(fragmentIds));
 			}
 		}
 		return getWrapped().getRenderIds();

spring-faces/src/test/java/org/springframework/faces/webflow/FlowPartialViewContextTests.java

@@ -16,6 +16,7 @@ import org.springframework.webflow.test.MockRequestContext;
 
 public class FlowPartialViewContextTests extends TestCase {
 
+	@SuppressWarnings("unchecked")
 	public void testReturnFragmentIds() throws Exception {
 		String[] fragmentIds = new String[] { "foo", "bar" };
 
@@ -46,4 +47,18 @@ public class FlowPartialViewContextTests extends TestCase {
 		assertEquals(renderIds, context.getRenderIds());
 	}
 
+	@SuppressWarnings("unchecked")
+	public void testReturnFragmentIdsMutable() throws Exception {
+		String[] fragmentIds = new String[] { "foo", "bar" };
+
+		RequestContext requestContext = new MockRequestContext();
+		requestContext.getFlashScope().asMap().put(View.RENDER_FRAGMENTS_ATTRIBUTE, fragmentIds);
+		RequestContextHolder.setRequestContext(requestContext);
+
+		Collection<String> renderIds = new FlowPartialViewContext(null).getRenderIds();
+		renderIds.add("baz");
+
+		assertEquals(Arrays.asList("foo", "bar", "baz"), renderIds);
+	}
+
 }