Adding Processing attribute to an XML spec

Hi Shashank_R 

OpenAPI specifications which are used in SwaggerHub don't directly support defining processing instructions-PIs like the one you provided at the beginning (<?TEST TEST1="100" TEST2="NONE"?>).

While it is not ideal, you can use comments within your YAML or JSON spec file to document the presence of the PI. For example:

# This API request expects an XML document with the following processing instruction:
# <?TEST TEST1="100" TEST2="NONE"?>
---
requestBody:
  required: true
  content:
    application/xml:
      schema:
        # ... your schema definition here 

You can also - use your client applications to handle the chosen approach.it's purely for documentation purposes.

Hope this helps - Happy to help further!!
Thank you very much and have a great one!
Warm regards