SAP
feature: Batch for GET function imports
Relates SAP/cloud-sdk-backlog#810.
This adds the function imports to the ReadRequests in batch. The POST related functions and action will go to the WriteRequests in a separate PR. Also response data transformation should be discussed. For the entities we have something like .as(entityApi) we could do something similar for the function import response. But first the basics.
Some function imports have not serializable entities. We removed the execute method for these. This caused type problems since the MethodRequestBuilder has an execute function. However, since batch does not need an execute, I removed it for all related request builders.
I also realized, that the CAP server expected the path to be relative to the entity, but the trippin worked with an absolute path.
