Properties defined within allOf omitted depending on ordering

Properties defined via an inline object definition as part of an allOf appear to be dropped when followed by a reference to a named type.

The following definition:

{
  "openapi": "3.0.3",
  "info": {
    "title": "Example",
    "version": "0.0.1"
  },
  "paths": {},
  "components": {
    "schemas": {
      "A": {
        "type": "object",
        "properties": {
          "a": { "type": "string" }
        }
      },
      "B": {
        "allOf": [
          {
            "type": "object",
            "properties": {
              "b": { "type": "string" }
            }
          },
          { "$ref": "#/components/schemas/A" }
        ]
      },
      "C": {
        "allOf": [
          { "$ref": "#/components/schemas/A" },
          {
            "type": "object",
            "properties": {
              "c": { "type": "string" }
            }
          }
        ]
      }
    }
  }
}

produces these models when run using the online tool - note that the property b is omitted from B:

type A struct {
	A string `json:"a,omitempty"`
}

type B struct {
	A string `json:"a,omitempty"`
}

type C struct {
	A string `json:"a,omitempty"`
	C string `json:"c,omitempty"`
}

Start by reproducing the supplied OpenAPI 3.0.3 example in the online tool and compare the generated Go models for B and C. Trace the allOf handling for inline object properties followed by a named $ref; done means B retains property b while C retains property c and both preserve property a.