[BUG] two levels of allOf forget parameter

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?
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Description

When there are two levels of allOf it seems that the properties in the middle are lost

openapi-generator version

5.2.1

OpenAPI declaration file content or url

https://github.com/Azure/azure-rest-api-specs/blob/3f4d11b1996c6da78de1e7d2765b7be390a8a38a/specification/eventhub/resource-manager/Microsoft.EventHub/stable/2017-04-01/namespaces.json

Generation Details

openapi-generator-cli generate \
-i specification/servicebus/resource-manager/Microsoft.ServiceBus/stable/2017-04-01/namespaces.json \
--api-package org.speefl.azure.api \
--model-package org.speefl.azure.api.model \
--invoker-package org.speefl.azure.api.invoker \
--group-id org.speedfl.azure-api-client \
--artifact-id namespaces \
--artifact-version 0.0-SNAPSHOT \
-g java \
-p java8=true \
-p apiTests=false \
-p modelTests=false \
--library microprofile \
-o /path/to/

Steps to reproduce

Clone repo: https://github.com/Azure/azure-rest-api-specs

openapi-generator-cli generate \
-i specification/servicebus/resource-manager/Microsoft.ServiceBus/stable/2017-04-01/namespaces.json \
--api-package org.speefl.azure.api \
--model-package org.speefl.azure.api.model \
--invoker-package org.speefl.azure.api.invoker \
--group-id org.speedfl.azure-api-client \
--artifact-id namespaces \
--artifact-version 0.0-SNAPSHOT \
-g java \
-p java8=true \
-p apiTests=false \
-p modelTests=false \
--library microprofile \
-o /path/to/

Look at the generated file: SBNamespace.java

It misses the location and tags properties located in specification/servicebus/resource-manager/common/v1/definitions.json

Run the supplied openapi-generator-cli command against the Azure servicebus namespaces.json input and inspect the generated SBNamespace.java. Compare it with the allOf definitions in common/v1/definitions.json, especially the location and tags properties. Done means those inherited properties are present in the generated Java model.