Unable to change image generation model for stability API

Bug description
I have a basic setup where I call stability image generation API with minimal options and I get a 404 error in API response.

404 - {"id":"0f91b262f6b5728385f167fe34688ec8","message":"The specified engine (ID stable-diffusion-v1-6) was not found.","name":"not_found"}

org.springframework.ai.retry.NonTransientAiException: 404 - {"id":"0f91b262f6b5728385f167fe34688ec8","message":"The specified engine (ID stable-diffusion-v1-6) was not found.","name":"not_found"}

When I tried changing the stability engine/model, it didn't work and I keep getting the same error back from API.

Environment
Development environment:
Java version: 21
Spring boot: 3.4.4
Spring AI: 1.0.3

Steps to reproduce
Here is a sample call to the stability API

stabilityAiImageModel.call(
            new ImagePrompt("A light cream colored mini golden doodle",
                StabilityAiImageOptions.builder()
                    .stylePreset("cinematic")
                    .N(1)
                    .height(512)
                    .model("stable-diffusion-xl-1024-v1-0")
                    .width(512).build())
                );

Above call results in 404 - Not found error mentioned above.

Expected behavior
Client should be able to chose the engine/model from stability to use for image generation.

Start with the StabilityAiImageModel.call invocation and StabilityAiImageOptions.builder shown in the issue, then inspect how the model option is sent to the Stability API. Reproduce the call with the supplied model value and verify that changing the model produces a request accepted by the API rather than the same 404 response.