Include error in the async response apis

[anandp504]

Pull Request: Update Response Schemas to Support Error Responses

Summary

Updated OpenAPI response schemas to support both successful responses and error responses using oneOf constraints. Responses now require context and exactly one of message or error.

Changes

Response Schema Pattern

• Before: required: [context, message] - only successful responses allowed
• After: required: [context] with oneOf requiring either message or error - supports both success and error responses

Updated Endpoints

All on_* callback endpoints now support error responses:

• /beckn/on_discover
• /beckn/on_select
• /beckn/on_init
• /beckn/on_confirm
• /beckn/on_status
• /beckn/on_update
• /beckn/on_cancel
• /beckn/on_support
• /beckn/on_track
• /beckn/on_rating
• /beckn/v2/catalog/on_publish
• /beckn/on_discover/offer

Schema Updates

• Added error property to response schemas. The error object structure:

  Error:
    type: object
    required: [code, message]
    properties:
      code:
        type: string
        description: Error code
        example: "INVALID_SCHEMA_FIELD"
      message:
        type: string
        description: Human-readable error message
        example: "Field 'electronic:invalidField' not found in ElectronicItem schema"
      details:
        type: object
        description: Additional error details

• Maintained backward compatibility - successful responses still work as before

[ravi-prakash-v]

Approved

[ravi-prakash-v]

@anandp504 can you fix the conflicts?