Rule idea: no-unnecessary-combinator

[silverwind]

A combinator like allOf, anyOf or oneOf with only a single member is useless and could trigger a warning:

openapi: 3.0.3
components:
  schemas:
    foo:
      type: string
    bar:
      allOf:
        - "$ref": "/components/schemas/foo"

Corrected, the schema for bar would be:

    bar:
      "$ref": "/components/schemas/foo"

[daveshanley]

Nice idea! will add it to the list