[SAPUI5] Add custom header parameter to all oData queries

Simply go to your Component.js file and add this line to the init function:

this.getModel().setHeaders({"myCustomParameter": "test"})

In a CAP Backend, you get this parameter from the express req object, which can be accessed via the req.http property:

req.http.req.headers['myCustomParameter']

And here is a nice code snippet, on how to read this header parameter in an ABAP system: https://answers.sap.com/answers/425621/view.html