Sensitive Context Properties
According to the documentation doing so will prevent its contents from being displayed in the Admin Console or HAT.
This is very good when you have to convey sensitive information in the context as part of your solution.
For instance – the password property in the SOAP adapter’s system property schema is marked as sensitive.
It is important to note though that marking a property as sensitive prevents you from promoting this property.
In some cases (when promoting through a schema) it will cause a design time error in in some cases (promoting through the
IBaseMessageContext.Promote, or in an assign shape as mentioned above) will create a runtime error.
If you will examine the event log entry generated by this runtime error you might see an initial error as an ArgumentOutOfRangeException with “Index and length must refer to a location within the string.” As its description
However, if you will look deeper you will see an InvalidPropertyValueException hiding in the stack call.
Having said all that, when I actually tried to work with a property marked as sensitive I could see it's value in both HAT and the Admin Console, so I have to admit I'm not quite sure what I have missed.