Incomplete - task 84: Fix samples

Fix restart sample - StepExecutionDao was not restoring execution context

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/ExecutionContext.java

@@ -99,7 +99,7 @@ public class ExecutionContext {
 
 		if (!type.isInstance(value)) {
 			throw new ClassCastException("Value for key=[" + key + "] is not of type: [" + type
-					+ "], it is [" + (value == null ? null : value) + "]");
+					+ "], it is [" + (value == null ? null : "("+value.getClass()+")"+value) + "]");
 		}
 
 		return value;