Sync with 3.1.x

* 3.1.x: (61 commits)
  Compensate for changes in JDK 7 Introspector
  Avoid 'type mismatch' errors in ExtendedBeanInfo
  Polish ExtendedBeanInfo and tests
  Infer AnnotationAttributes method return types
  Minor fix in MVC reference doc chapter
  Hibernate 4.1 etc
  TypeDescriptor equals implementation accepts annotations in any order
  "setBasenames" uses varargs now (for programmatic setup; SPR-9106)
  @ActiveProfiles mechanism works with @ImportResource as well (SPR-8992
  polishing
  clarified Resource's "getFilename" method to consistently return null
  substituteNamedParameters detects and unwraps SqlParameterValue object
  Replace spaces with tabs
  Consider security in ClassUtils#getMostSpecificMethod
  Adding null check for username being null.
  Improvements for registering custom SQL exception translators in app c
  SPR-7680 Adding QueryTimeoutException to the DataAccessException hiera
  Minor polish in WebMvcConfigurationSupport
  Detect overridden boolean getters in ExtendedBeanInfo
  Polish ExtendedBeanInfoTests
  ...

spring-webmvc-portlet/src/main/java/org/springframework/web/portlet/context/PortletContextResource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -107,6 +107,28 @@ public class PortletContextResource extends AbstractFileResolvingResource implem
 		}
 	}
 
+	/**
+	 * This implementation delegates to <code>PortletContext.getResourceAsStream</code>,
+	 * which returns <code>null</code> in case of a non-readable resource (e.g. a directory).
+	 * @see javax.portlet.PortletContext#getResourceAsStream(String)
+	 */
+	@Override
+	public boolean isReadable() {
+		InputStream is = this.portletContext.getResourceAsStream(this.path);
+		if (is != null) {
+			try {
+				is.close();
+			}
+			catch (IOException ex) {
+				// ignore
+			}
+			return true;
+		}
+		else {
+			return false;
+		}
+	}
+
 	/**
 	 * This implementation delegates to <code>PortletContext.getResourceAsStream</code>,
 	 * but throws a FileNotFoundException if not found.