message: Updates to x-nullable
  Make clear that null array entries are not supported.
  Tweaked dictionary example for clarity.
diff: @@ -1009,7 +1009,7 @@ When set, specifies the header parameter to be used instead of `x-ms-client-requ
  ## x-nullable
  Set `"x-nullable": true` on a schema to indicate that a `null` is a legal value. By default, a `null` value should be disallowed when forming a request and rejected during payload deserialization.
  -When deserializing arrays, any `null` entries in the array should simply be discarded.
  +For arrays, sending/receiving a `null` array entry is not supported and should result in an error.
  **Example**:
  An operation that returns a scalar value or null.
  @@ -1050,7 +1050,7 @@ A dictionary where a key's value can be null.
  "schema": {
  "description": "Credential key/value pairs. Set the credential key's value to null to remove the credential.",
  "type": "object",
  - "additionalProperties": {
  + "credentials": {
  "type": "object",
  "additionalProperties": {
  "type": "string",
  