added proper "contentLength()" implementation to ByteArrayResource (SPR-8709)

org.springframework.core/src/main/java/org/springframework/core/io/ByteArrayResource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2007 the original author or authors.
+ * Copyright 2002-2011 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.
@@ -80,6 +80,14 @@ public class ByteArrayResource extends AbstractResource {
 		return true;
 	}
 
+	/**
+	 * This implementation returns the length of the underlying byte array.
+	 */
+	@Override
+	public long contentLength() {
+		return this.byteArray.length;
+	}
+
 	/**
 	 * This implementation returns a ByteArrayInputStream for the
 	 * underlying byte array.