OpenAPI generation: fix properties alongside $refs are ignored

[Yauhenikapl]

OpenAPI generation: fix properties alongside $refs are ignored and roll back items in items for array type fix

Description

Please include a summary of the changes and the related issue. List any dependencies that are required for this change.

Fixes #761

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works

Additional notes

[Yauhenikapl]

This logic fixing this structure:

"PagingSchema" : {
        "type" : "object",
        "properties" : {
          ...
          "items" : {
            "type" : "array",
            "items" : {
              "$ref" : "#/components/schemas/AspectWithErrorCollection"
            }
          }
        }
      },

to this:

"PagingSchema" : {
        "type" : "object",
        "properties" : {
          ...
          "aspectItems" : {
            "type" : "array",
            "items" : {
              "$ref" : "#/components/schemas/AspectWithErrorCollection"
            }
          }
        }
      },

It means, that attribute "items" will be taken from property name and not by default "items".

@atextor