Mixed JSON and other content throws a warning for JSON filter

[Andrew_LeCody]

Despite having skip_on_invalid_json set to true I keep getting errors on content that isn't purely json, but is a mix of json and other content (null, int, strings).

Here's my filter config:

filter {
  json {
    source => "message"
    skip_on_invalid_json => true
  }
  mutate {
    lowercase => [ "logGroup" ]
  }
}

And here are some example warnings I'm getting in my logs:

[2020-01-22T22:52:07,697][WARN ][logstash.filters.json    ] Parsed JSON object/hash requires a target configuration option {:source=>"message", :raw=>"{\"timestamp\":\"2020-01-22T22:51:47.940Z\",\"log_level\":\"INFO\",\"caller\":\"redacted\",\"invoke_id\":\"redacted\"} \"Input Phase is old or ManagedInfo Success is timeout or cancel. [Input Phase=2, ManagedInfo Phase=4,Success=0]\"\n"}

[2020-01-22T22:52:07,707][WARN ][logstash.filters.json    ] Parsed JSON object/hash requires a target configuration option {:source=>"message", :raw=>"{\"timestamp\":\"2020-01-22T22:51:41.675Z\",\"log_level\":\"INFO\",\"caller\":\"redacted\",\"invoke_id\":\"redacted\"} 2001222251312800\n"}

[2020-01-22T22:55:11,134][WARN ][logstash.filters.json    ] Parsed JSON object/hash requires a target configuration option {:source=>"message", :raw=>"{\"timestamp\":\"2020-01-22T22:54:58.479Z\",\"log_level\":\"INFO\",\"caller\":\"redacted\",\"invoke_id\":\"redacted\"} null"}

The logs do get placed into elasticsearch, but the logstash logs are filling up with warnings since this is a very high volume stream.