Exception details are lost when constructor with operation name is used.

When the exception is thrown with operation name the original errorMessage is lost.
For example

```
throw new CfnGeneralServiceException("Operation", new RuntimeException("something happend");
```

results in `"Error occurred during operation 'Operation'."` message.

If operation parameter would not be passed

```
throw new CfnGeneralServiceException(new RuntimeException("something happend")
```

then the message would contain `"something happend"`.

There are existing implementation's of resources that rethrow exceptions with operation field set, and the original message is thrown. What is more - if any exception will be unhandled explicitly `CfnInternalFailureException` will be thrown without errorMessage from the original exception and CloudFormation console will just display "Internal failure... " kind of message