partial Env/Store Variables not expanded for plugins using Java Plugin API

[111andre111]

At the moment environment and secure store variables are not being expanded in partial strings before plugins developed using the Java Plugin API are initialized.

To replicate, first you will need to export an environment variable FOO (or add it to the truststore):

  export FOO=bar

started logstash at first with the old ruby world with message containing variable only:

#  bin\logstash --java-execution false -e 'input { generator { message => "${FOO}" count => 1} } output { stdout { codec => rubydebug } }'
{
      "sequence" => 0,
          "host" => "COMPUTER",
       "message" => "bar",
    "@timestamp" => 2020-03-27T17:09:20.446Z,
      "@version" => "1"
}

--> ok

And now a message with message containing variable as a part:

# bin\logstash --java-execution false -e 'input { generator { message => "${FOO}sage" count => 1} } output { stdout { codec => rubydebug } }'
{
      "sequence" => 0,
          "host" => "COMPUTER",
       "message" => "barsage",
    "@timestamp" => 2020-03-27T17:09:21.784Z,
      "@version" => "1"
}

--> ok

Then the same for the Java Plugin world with message containing variable only:

  bin\logstash --java-execution true -e 'input { java_generator { message => "${FOO}" count => 1} } output { stdout { codec => rubydebug } }'
{
    "thread_number" => 0,
       "@timestamp" => 2020-03-27T17:10:44.431Z,
          "message" => "bar",
         "sequence" => 0,
         "hostname" => "COMPUTER",
         "@version" => "1"
}

ok -> solved in #10973 -> #11043

And again with message containing variable as a part:

  bin\logstash --java-execution true -e 'input { java_generator { message => "${FOO}sage" count => 1} } output { stdout { codec => rubydebug } }'
{
          "message" => "${FOO}sage",
         "sequence" => 0,
         "@version" => "1",
       "@timestamp" => 2020-03-27T17:11:47.759Z,
    "thread_number" => 0,
         "hostname" => "COMPUTER"
}
-->  nok
This last part doesn't seem to work.