syndesis: Error in data mapper when editing an API Provider flow which changed due to API definition change

See also https://issues.jboss.org/browse/ENTESB-11434

This is a…

[ ] Feature request
[ ] Regression (a behavior that used to work and stopped working in a new release)
[x] Bug report  
[ ] Documentation issue or request

Description

In an API Provider integration, after changing the return type of an operation that’s already implemented, trying to update the data mapping causes the following error:

Data Mapper UI Initialization Error: Could not load document 'i-LaUfMv856-V-nkQhsB7z': undefined undefined 

Steps to reproduce:

1. create an API Provider integration with a flow that requires a data mapping
2. edit the operation so that the data mapping would not be valid (e.g. change the return type)
3. save the API definition
4. open the appropriate flow, notice a warning badge on the result
5. open the data mapper to change the mapping, the above error is shown