Incorrect data type conversion

[masech]

• Version: 7.8.1 and earlier
• Operating System: CentOS 7, Ubuntu 18.04
• Config File:

input {
    generator {
        lines => [
            "1.0.0.0",
            "0.0.0.0"
        ]
        count => 1
    }
}

filter {
    dissect {
        mapping => {
            "message" => "%{octet_1}.%{octet_2}.%{octet_3}.%{octet_4}"
        }
        convert_datatype => {
            "octet_1" => "int"
            "octet_2" => "int"
            "octet_3" => "int"
            "octet_4" => "int"
        }
    }

    if ([octet_1] != 0) {
        #add field 'TRUE' if 'octet_1' is not zero
        mutate {
            add_field => {
                "TRUE" => "Get True"
            }
        }

    } else {
        #add field 'FALSE' if 'octet_1' is zero
        mutate {
            add_field => {
                "FALSE" => "Get False"
            }
        }
    }
}

output {
    stdout {
        codec => rubydebug
    }
}

• Expected output:

{
          "TRUE" => "Get True",
       "octet_1" => 1,
       "octet_3" => 0,
       "octet_2" => 0,
       "octet_4" => 0,
       "message" => "1.0.0.0"
}
{
          "FALSE" => "Get False",
       "octet_1" => 0,
       "octet_3" => 0,
       "octet_2" => 0,
       "octet_4" => 0,
       "message" => "0.0.0.0"
}

• Actual output:

{
          "TRUE" => "Get True",
       "octet_1" => 1,
       "octet_3" => 0,
       "octet_2" => 0,
       "octet_4" => 0,
       "message" => "1.0.0.0"
}
{
          ""TRUE" => "Get True",
       "octet_1" => 0,
       "octet_3" => 0,
       "octet_2" => 0,
       "octet_4" => 0,
       "message" => "0.0.0.0"
}

• Steps to Reproduce: the pipeline.java_execution setting in the /etc/logstash/logstash.yml file must be enabled (value is true)