Telegraf Timestamp format (ts-epochmilli)

[fedeori]

When parsing a CSV file (obtained from Jmeter) with telegraf logparser, the first field is an epoch timestamp in milliseconds, and when i try to set it as ts-epochmilli, telegraf can't parse it to that format.
When i try to use just the ts option (any timestamp) telegraf can not find any suitable time layout.

Relevant telegraf.conf:

files = ["/path/to/input.log"]
from_beginning = true
name_override = "metric_name"
watch_method = "poll"

[inputs.logparser.grok]
patterns = ["%{CUSTOM_JMETER}"]
custom_patterns = '''
CUSTOM_JMETER %{POSINT:timestamp:ts-epochmilli},%{INT:elapsed:int},("%{DATA:label}"|%{DATA:label}),%{WORD:responseCode:string},("%{DATA:responseMsg}"|%{DATA:responseMsg}),("%{DATA:threadName}"|%{DATA:threadName}),("%{DATA:datatype}"|%{DATA:datatype}),%{WORD:success},("%{DATA:failureMessage}"|%{DATA:failureMessage}),%{INT:bytes:int},%{INT:sentBytes:int},%{INT:grpThreads:int},%{INT:allThreads:int},("%{DATA:url}"|%{DATA:url}),%{INT:Latency:int},%{INT:IdleTime:int},%{INT:Connect:int}
'''

System info:

Tested in telegraf-1.12.6 in windows an linux (CentOs).

Steps to reproduce:

Configure telegraf as shown above, using the attached file as input (it is a standard jmeter csv output). Configure output to influxdb.

Expected behavior:

Import the data using the first field as timestamp.

Actual behavior:

There's an error parsing timestamp to ts-epochmilli .
2019-11-21T23:26:06Z E! Error parsing 1574293698744 to time layout [ts-epochmilli]: parsing time "1574293698744" as "ts-epochmilli": cannot parse "1574293698744" as "ts-epochmilli"
2019-11-21T23:26:06Z E! Error parsing 1574293698745 to time layout [ts-epochmilli]: parsing time "1574293698745" as "ts-epochmilli": cannot parse "1574293698745" as "ts-epochmilli"
2019-11-21T23:26:06Z E! Error parsing 1574293699931 to time layout [ts-epochmilli]: parsing time "1574293699931" as "ts-epochmilli": cannot parse "1574293699931" as "ts-epochmilli"

With ts format
2019-11-21T23:46:20Z E! Error parsing timestamp [1574293698744], could not find any suitable time layouts.
2019-11-21T23:46:20Z E! Error parsing timestamp [1574293698745], could not find any suitable time layouts.
2019-11-21T23:46:20Z E! Error parsing timestamp [1574293699931], could not find any suitable time layouts.
2019-11-21T23:46:20Z E! Error parsing timestamp [1574293699931], could not find any suitable time layouts.
2019-11-21T23:46:20Z E! Error parsing timestamp [1574293700992], could not find any suitable time layouts.
2019-11-21T23:46:20Z E! Error parsing timestamp [1574293701003], could not find any suitable time layouts.
If i try with ts telegraf cant find the wright format.

Additional info:

input.log

[danielnelson]

This time layout was added in #6476 and will be first released in Telegraf 1.13.0.