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

[wesolowskim]

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