💡 Creating duplicate Credential Definition should return Credential Definition

[rblaine95]

When creating a duplicate Credential Schema, the response is the already existing Credential Schema:

{
  "id": "Hd7nmadkMM7oayBNpkQJzU:2:test_schema:0.3",
  "name": "test_schema",
  "version": "0.3.0",
  "attribute_names": [
    "speed"
  ]
}

However, when creating a duplicate Credential Definition, the response is 400 with a "this definition already exists" message:

{
  "detail": "Cred def for Hd7nmadkMM7oayBNpkQJzU:2:test_schema:0.3.0 asdf already exists"
}

Instead of the already existing Credential Definition:

{
  "id": "NcfXjRU9dvhe291FR5tymb:3:CL:18:assdddffff",
  "tag": "assdddffff",
  "schema_id": "Hd7nmadkMM7oayBNpkQJzU:2:test_schema:0.3.0"
}

In my opinion, for things closely related (like Credential Definitions and Schemas), the response for duplicates should behave the same.
Instead of erroring with a "this already exists" message, it should respond as though the creation was successful and return the already existing definition.

MT Web logs when creating duplicate Credential Definition:

2023-10-04 09:02:39.751 | DEBUG    | app.routes.definitions:create_credential_definition:224 | Publishing credential definition | tag='asdf' schema_id='Hd7nmadkMM7oayBNpkQJzU:2:test_schema:0.3.0' support_revocation=True revocation_registry_size=32767
INFO:     127.0.0.6:57209 - "POST /generic/definitions/credentials HTTP/1.1" 400 Bad Request
ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/uvicorn/protocols/http/httptools_impl.py", line 426, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
  File "/usr/local/lib/python3.9/site-packages/uvicorn/middleware/proxy_headers.py", line 84, in __call__
    return await self.app(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/fastapi/applications.py", line 292, in __call__
    await super().__call__(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/applications.py", line 122, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/errors.py", line 184, in __call__
    raise exc
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/errors.py", line 162, in __call__
    await self.app(scope, receive, _send)
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/exceptions.py", line 79, in __call__
    raise exc
  File "/usr/local/lib/python3.9/site-packages/starlette/middleware/exceptions.py", line 68, in __call__
    await self.app(scope, receive, sender)
  File "/usr/local/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 20, in __call__
    raise e
  File "/usr/local/lib/python3.9/site-packages/fastapi/middleware/asyncexitstack.py", line 17, in __call__
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/routing.py", line 718, in __call__
    await route.handle(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/routing.py", line 276, in handle
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.9/site-packages/starlette/routing.py", line 66, in app
    response = await func(request)
  File "/usr/local/lib/python3.9/site-packages/fastapi/routing.py", line 273, in app
    raw_response = await run_endpoint_function(
  File "/usr/local/lib/python3.9/site-packages/fastapi/routing.py", line 190, in run_endpoint_function
    return await dependant.call(**values)
  File "/app/routes/definitions.py", line 225, in create_credential_definition
    result = await aries_controller.credential_definition.publish_cred_def(
  File "/usr/local/lib/python3.9/site-packages/aries_cloudcontroller/api/credential_definition.py", line 79, in publish_cred_def
    return await self.__publish_cred_def(
  File "/usr/local/lib/python3.9/site-packages/uplink/clients/io/asyncio_strategy.py", line 32, in execute
    return await executable.execute()
  File "/usr/local/lib/python3.9/site-packages/uplink/clients/io/asyncio_strategy.py", line 19, in invoke
    response = await callback.on_failure(type(error), error, tb)
  File "/usr/local/lib/python3.9/site-packages/uplink/clients/io/asyncio_strategy.py", line 19, in invoke
    response = await callback.on_failure(type(error), error, tb)
  File "/usr/local/lib/python3.9/site-packages/uplink/clients/io/asyncio_strategy.py", line 19, in invoke
    response = await callback.on_failure(type(error), error, tb)
  File "/usr/local/lib/python3.9/site-packages/uplink/clients/io/execution.py", line 108, in on_failure
    return self._io.fail(exc_type, exc_val, exc_tb)
  File "/usr/local/lib/python3.9/site-packages/uplink/clients/io/execution.py", line 128, in fail
    return self._io.fail(exc_type, exc_val, exc_tb)
  File "/usr/local/lib/python3.9/site-packages/uplink/clients/io/interfaces.py", line 300, in fail
    compat.reraise(exc_type, exc_val, exc_tb)
  File "/usr/local/lib/python3.9/site-packages/six.py", line 719, in reraise
    raise value
  File "/usr/local/lib/python3.9/site-packages/uplink/clients/io/asyncio_strategy.py", line 16, in invoke
    response = await func(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/uplink/builder.py", line 47, in wrapper
    return func(self._consumer, *args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/uplink/hooks.py", line 110, in handle_exception
    compat.reraise(exc_type, exc_val, exc_tb)
  File "/usr/local/lib/python3.9/site-packages/six.py", line 719, in reraise
    raise value
  File "/usr/local/lib/python3.9/site-packages/uplink/clients/io/asyncio_strategy.py", line 16, in invoke
    response = await func(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/uplink/builder.py", line 47, in wrapper
    return func(self._consumer, *args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/uplink/hooks.py", line 110, in handle_exception
    compat.reraise(exc_type, exc_val, exc_tb)
  File "/usr/local/lib/python3.9/site-packages/six.py", line 719, in reraise
    raise value
  File "/usr/local/lib/python3.9/site-packages/uplink/clients/io/asyncio_strategy.py", line 16, in invoke
    response = await func(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/uplink/clients/aiohttp_.py", line 133, in send
    response = await session.request(method, url, **extras)
  File "/usr/local/lib/python3.9/site-packages/aiohttp/client.py", line 643, in _request
    resp.raise_for_status()
  File "/usr/local/lib/python3.9/site-packages/aiohttp/client_reqrep.py", line 1005, in raise_for_status
    raise ClientResponseError(
aiohttp.client_exceptions.ClientResponseError: 400, message='Cred def for Hd7nmadkMM7oayBNpkQJzU:2:test_schema:0.3.0 asdf already exists', url=URL('http://governance-multitenant-agent:4021/credential-definitions')