Add drone.io CI for Java 11 test (#3472)

* add drone.yml

* use maven wrapper instead

* break the build

* Revert "break the build"

This reverts commit 69769d6cadd4c25ea5e8c5ed2bc5115ec29b0ecb.

* add drone.io badge to README

* update wording

CI/.drone.yml

@@ -0,0 +1,9 @@
+kind: pipeline
+name: default
+
+steps:
+- name: test
+  image: hirokimatsumoto/alpine-openjdk-11	
+  commands:
+  - ./mvnw clean install
+  - ./mvnw --quiet verify -Psamples.droneio

README.md

@@ -6,11 +6,13 @@
 [![Integration Test2](https://circleci.com/gh/OpenAPITools/openapi-generator.svg?style=shield)](https://circleci.com/gh/OpenAPITools/openapi-generator)
 [![Run Status](https://api.shippable.com/projects/5af6bf74e790f4070084a115/badge?branch=master)](https://app.shippable.com/github/OpenAPITools/openapi-generator)
 [![Windows Test](https://ci.appveyor.com/api/projects/status/github/openapitools/openapi-generator?branch=master&svg=true&passingText=Windows%20Test%20-%20OK&failingText=Windows%20Test%20-%20Fails)](https://ci.appveyor.com/project/WilliamCheng/openapi-generator-wh2wu)
+[![JDK11 Build](https://cloud.drone.io/api/badges/OpenAPITools/openapi-generator/status.svg?ref=refs/heads/master)](https://cloud.drone.io/OpenAPITools/openapi-generator)
 
 [`5.0.x`](https://github.com/OpenAPITools/openapi-generator/tree/5.0.x) branch: [![Build Status](https://img.shields.io/travis/OpenAPITools/openapi-generator/5.0.x.svg?label=Integration%20Test)](https://travis-ci.org/OpenAPITools/openapi-generator)
 [![Integration Test2](https://circleci.com/gh/OpenAPITools/openapi-generator/tree/5.0.x.svg?style=shield)](https://circleci.com/gh/OpenAPITools/openapi-generator)
 [![Run Status](https://api.shippable.com/projects/5af6bf74e790f4070084a115/badge?branch=5.0.x)](https://app.shippable.com/github/OpenAPITools/openapi-generator)
 [![Windows Test](https://ci.appveyor.com/api/projects/status/github/openapitools/openapi-generator?branch=5.0.x&svg=true&passingText=Windows%20Test%20-%20OK&failingText=Windows%20Test%20-%20Fails)](https://ci.appveyor.com/project/WilliamCheng/openapi-generator-wh2wu)
+[![JDK11 Build](https://cloud.drone.io/api/badges/OpenAPITools/openapi-generator/status.svg?ref=refs/heads/5.0.x)](https://cloud.drone.io/OpenAPITools/openapi-generator)
 </div>
 
 <div align="center">

pom.xml

@@ -1244,6 +1244,20 @@
                 <module>samples/server/petstore/spring-mvc-j8-localdatetime</module>
             </modules>
         </profile>
+        <!-- test with JDK11 in drone.io -->
+        <profile>
+            <id>samples.droneio</id>
+            <activation>
+                <property>
+                    <name>env</name>
+                    <value>samples.droneio</value>
+                </property>
+            </activation>
+            <modules>
+                <!-- clients -->
+                <module>samples/client/petstore/java/native</module>
+            </modules>
+        </profile>
         <!-- test with Haskell -->
         <profile>
             <id>samples.misc</id>