Only the first missing required field is returned in error message

[briangweber]

Describe the bug
If multiple required fields are omitted from the request body, only the first is reported missing in the error message.

To Reproduce
Make an empty object PUT request to /pet with this defintion

paths:
  /pet:
    put:
      tags:
        - pet
      summary: Update an existing pet
      description: Update an existing pet by Id
      operationId: updatePet
      requestBody:
        description: Update an existent pet in the store
        content:
          application/json:
            schema:
              required:
                - name
                - color
              type: object
              properties:
                name:
                  type: string
                  example: doggie
                color:
                  type: string
                  example: brown

Actual behavior
Error: must have required property 'name'

Expected behavior
Errors: must have required property 'name' and must have required property 'color'