fix(#523): handle missing 200 and default response in swagger test generation

[phos-web]

Description
Fixes the Swagger test generator crashing when an API operation defines no 200 or default response. The generator now falls back to the first available response in the spec and resolves its actual HTTP status code, instead of assuming a successful response always exists. If the status code cannot be resolved, the fallback remains 200 OK.

Related issue
Fixes #523

[bbortt]

isn't firstEntry null if there are no responses at all? this will throw a NoSuchElementException in that case.

test:

    @Test
    public void shouldCreateClassFromSpecWithNoResponses() throws IOException {
        SwaggerJavaTestGenerator generator = new SwaggerJavaTestGenerator();

        generator.withAuthor("phos-web")
                .withDescription("This is a sample test")
                .usePackage("org.citrusframework")
                .withFramework(UnitFramework.TESTNG);

        generator.withMode(TestGenerator.GeneratorMode.SERVER);
        generator.withSpec("org/citrusframework/swagger/api-with-no-responses.json");

        generator.create();

        verifyTest("PetApiClient_getPetById_IT");
        verifyTestWithStatus("PetApiClient_updatePet_IT", "BAD_REQUEST");
    }

api-with-no-responses.json

[phos-web]

Changed it to

if (response == null && !operation.getValue().getResponses().isEmpty())

[bbortt]

Suggested change

	httpStatus = HttpStatus.OK;
	// Ignore, default value is already HttpStatus.OK;