Which SNMP versions are supported for snmptrap plugin?

I’m trying logstash with snmptrap,
The following log was generated .

{
" #< SNMP::SNMPv2_Trap:0xc6fb838 @request_id=19345, @error_index=0, @error_status=0,
@source_ip="1.2.3.4", @varbind_list=[#<SNMP::VarBind:0x2c4c434d @name=[1.3.6.1.2.1.1.3.0], @value=#<SNMP::TimeTicks:0x220bf58c @value=922846876>>, #<SNMP::VarBind:0x53d4378d @name=[1.3.6.1.6.3.1.1.4.1.0], @value=[1.3.6.1.4.1.3607.2.20.0.2030]>, #<SNMP::VarBind:0x29e031c1 @name=[1.3.6.1.4.1.3607.2.10.10.20.0], @value="20160425202213S">, #<SNMP::VarBind:0x67f8599b @name=[1.3.6.1.4.1.3607.2.10.30.20.1.80.1.2030], @value=#<SNMP::Integer:0x1aa2777d @value=31>>, #<SNMP::VarBind:0x68b843fb @name=[1.3.6.1.4.1.3607.2.10.30.20.1.20.1.2030], @value=#<SNMP::Integer:0x407e1914 @value=10>>, #<SNMP::VarBind:0x656fb401 @name=[1.3.6.1.4.1.3607.2.10.30.20.1.60.1.2030], @value=#<SNMP::Integer:0x6c7f2e4e @value=1>>, #<SNMP::VarBind:0x46720fa1 @name=[1.3.6.1.4.1.3607.2.10.30.20.1.30.1.2030], @value=#<SNMP::Integer:0x76f408c2 @value=0>>, #<SNMP::VarBind:0x6ea375a1 @name=[1.3.6.1.4.1.3607.2.10.30.20.1.40.1.2030], @value=#<SNMP::Integer:0x7bbb3b65 @value=1>>, #<SNMP::VarBind:0x2d622cb4 @name=[1.3.6.1.4.1.3607.2.10.30.20.1.50.1.2030], @value=#<SNMP::Integer:0x7b0683c2 @value=0>>, #<SNMP::VarBind:0xefdef7e @name=[1.3.6.1.4.1.3607.2.10.30.20.1.100.1.2030], @value="SYSTEM">, #<SNMP::VarBind:0x2cbf9dd7 @name=[1.3.6.1.6.3.18.1.3.0], @value=#<SNMP::IpAddress:0x10841378 @value="\xC0\xA8\v\x0F">>]>",
"@timestamp" => "2016-04-25T12:22:08.982Z",
"@version" => "1",
"source_ip" => "1.2.3.4",
}

my configuration ,

input {
   snmptrap {
   type => "snmp_trap"
      }
}
output {
        stdout {
        codec => rubydebug
     }
 }

why the @version in output is 1 ?
is it only v1 supported ?
snmptrap plugin does not talk about which versions of SNMP are supported?

why the @version in output is 1 ?

That's unrelated to SNMP. It's the version number of the Logstash event schema.

Yes, I would like to know too. The example you provided indicates SNMPV2 (probably v2c).

I would like for someone to say definitively if the snmptrap plugin supports SNMP V3.