[BUG] can't generate security definitions like api key

[kannkyo]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

Openapi-generator can't generate generate security definitions like api key.

openapi-generator version

master branch at a4f1d1b

OpenAPI declaration file content or url

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/test/resources/2_0/petstore.yaml

Generation Details

When I execute bellow command to generate jemeter files,

git clone https://github.com/OpenAPITools/openapi-generator
mvn install -Dmaven.test.skip=true
./bin/generate-samples.sh bin/configs/other/jmeter.yaml 

jmeter fiels don't have api key in headers.

actual output

<ThreadGroup guiclass="ThreadGroupGui" testclass="ThreadGroup" testname="Thread Group - getPetById" enabled="true">
...
        <HeaderManager guiclass="HeaderPanel" testclass="HeaderManager" testname="HTTP Header Manager" enabled="true">
          <collectionProp name="HeaderManager.headers">
          </collectionProp>
        </HeaderManager>

expected output

<ThreadGroup guiclass="ThreadGroupGui" testclass="ThreadGroup" testname="Thread Group - getPetById" enabled="true">
...
        <HeaderManager guiclass="HeaderPanel" testclass="HeaderManager" testname="HTTP Header Manager" enabled="true">
          <collectionProp name="HeaderManager.headers">
            <elementProp name="" elementType="Header">
              <stringProp name="Header.name">api_key</stringProp>
              <stringProp name="Header.value">${__P(apiKey,key)}</stringProp>
            </elementProp>
          </collectionProp>
        </HeaderManager>

Steps to reproduce

see "Generation Details"

Related issues/PRs

nothing

Suggest a fix

change https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/jmeter-client/api.mustache