Handle EventTime Forward protocol v1 extension

[cosmo0920]

Currently, Fluentd v1.0's Forward protocol EventTime extension cannot handle in logstash-codec-fluent.

see: https://github.com/fluent/fluentd/wiki/Forward-Protocol-Specification-v1#eventtime-ext-format

• Version: 3.1.5 and 3.2.0
• Operating System: macOS and Linux
• Config File (if you have sensitive info, please remove it):

input {
  tcp {
    codec => fluent
    port => 24224
  }
}
output {
  stdout { codec => json }

• Sample Data and Steps to Reproduce:

1. Install td-agent3
2. execute fluent-cat with EventTime extension:

$  echo '{"current_version":"v0.14", "versions":{"unstable":0.14, "stable":0.12}}' | fluent-cat my.logs

• Expected Result

Output json log with subsecond included timestamp like as:

{"@metdata":{"ip_address":"127.0.0.1"},"host":"localhost","versions":{"stable":0.12,"unstable":0.14},"tags":["my.logs"],"current_version":"v0.14","@version":"1","@timestamp":"2018-01-15T06:38:03.432Z","port":53918}

• Actual Result

Nothing output when enabling EventTime msgpack extension. (This is default behavior for Fluentd v1.0)

• Fixing Candidates Patch

#18.

[cosmo0920]

#18 is already merged. Closing.