Use Thread ContextClassLoader in ConfigurableObjectInputStream

Issue: SWF-1690

Author: rstoyanchev

spring-webflow/src/main/java/org/springframework/webflow/execution/repository/snapshot/SerializedFlowExecutionSnapshot.java

@@ -248,7 +248,12 @@ private static class ConfigurableObjectInputStream extends ObjectInputStream {
 
 		public ConfigurableObjectInputStream(InputStream in, ClassLoader classLoader) throws IOException {
 			super(in);
-			this.classLoader = classLoader;
+			this.classLoader = initClassLoader(classLoader);
+		}
+
+		private static ClassLoader initClassLoader(ClassLoader defaultClassLoader) {
+			ClassLoader result = Thread.currentThread().getContextClassLoader();
+			return result != null ? result : defaultClassLoader;
 		}
 
 		protected Class<?> resolveClass(ObjectStreamClass desc) throws IOException, ClassNotFoundException {