NPE in Oas*ExamplesMutualExclusivityRule for single example

[tjuerge]

With activated global validity rule (Full) uploading an OpenAPI artifact using a single example (instead of multiple examples) an NPE is thrown and following error is shown:

Example artifact:

openapi: 3.0.3

info:
  title: Test
  version: 1.0.0

paths:
  /v1/test:
    get:
      operationId: test
      parameters:
        - name: PARAM
          in: header
          schema:
            type: string
          example: "myparam"   # <- culprit
      responses:
        '200':
          description: OK 

Searching for getExamples().size() shows where possibly a null check is missing: