ignore_missing parameter is missing on "remove" pipeline processor

[ccelson]

Elasticsearch version: 5.1

Plugins installed:

JVM version: 1.8.0_121-b13

OS version: Mac OS 10.10.5

Description of the problem including expected versus actual behavior:
"Remove" Pipeline processor does not all allow for the "ignore_missing" parameter.

Steps to reproduce:
1.

POST _ingest/pipeline/_simulate
{
  "pipeline": {
    "description": "remove specific fields",
    "processors": [
      {
        "remove": {
          "field": "to_remove",
          "ignore_missing": true
        }
      }
    ]
  },
  "docs": [
    {
      "field1": "field1"
    }
  ]
}

Results in

{
  "error": {
    "root_cause": [
      {
        "type": "parse_exception",
        "reason": "processor [remove] doesn't support one or more provided configuration parameters [ignore_missing]",
        "header": {
          "processor_type": "remove"
        }
      }
    ],
    "type": "parse_exception",
    "reason": "processor [remove] doesn't support one or more provided configuration parameters [ignore_missing]",
    "header": {
      "processor_type": "remove"
    }
  },
  "status": 400
}

I would expect the "ignore_missing" parameter to be available on the remove processor.

[talevy]

@ccelson thanks for the report! I will go ahead and add the ignore_missing flag. For the time being, maybe try ignore_failure[1]

[elasticmachine]

Pinging @elastic/es-core-infra