Retain operation level parameters over path level ones

[arthurcro]

Motivation

Fixes #168.

Modifications

Previously, an operation's parameters were returned as a concatenation of the parameters from the path item level with those at operation level.

However, this is incorrect according to https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.3.md#fixed-fields-7.

A list of parameters that are applicable for all the operations described under this path. These parameters can be overridden at the operation level, but cannot be removed there. The list MUST NOT include duplicated parameters.

With this change, we are merging the two arrays of parameters using a unique identifier of the location + name of parameters. If duplicate parameters exist, only the parameters from the operation level are preserved.

Result

After this change, an operation's parameters won't contain any duplicate.

Test Plan

Add tests for OperationDescription.allParameters at Tests/OpenAPIGeneratorCoreTests/Translator/Operations/Test_OperationDescription.swift.

[czechboy0]

The change looks good, just a few minor style suggestions.

For testing, you can create a new unit test file Tests/OpenAPIGeneratorCoreTests/Translator/Operations/Test_OperationDescription.swift, follow the style seen e.g. in Tests/OpenAPIGeneratorCoreTests/Translator/Content/Test_ContentType.swift, and create an OperationDescription with duplicated params in the path and operation in the unit test and verify that allParameters returns just the unique ones.

[arthurcro]

Thank you for the nice review, I applied all suggestions! 🙂
I'll add a test shortly and mark this as ready for review.

[czechboy0]

@swift-server-bot add to allowlist

[czechboy0]

Just two more comments about the tests, otherwise looks great!

[czechboy0]

Awesome, thank you!