Test Gradle plugin in Appveyor CI (OpenAPITools#2651)

* update travis to test gradle plugin

* update gradle version

* show gradle version

* test gradle plugin in circleci

* test appveyor in gradle

* use direct link

* revert other ci config

appveyor.yml

@@ -14,11 +14,23 @@ install:
         )
         [System.IO.Compression.ZipFile]::ExtractToDirectory("C:\maven-bin.zip", "C:\maven")
       }
-  - cmd: SET PATH=C:\maven\apache-maven-3.2.5\bin;%JAVA_HOME%\bin;%PATH%
+  # install gradle
+  - ps: |
+      Add-Type -AssemblyName System.IO.Compression.FileSystem
+      if (!(Test-Path -Path "C:\gradle" )) {
+        (new-object System.Net.WebClient).DownloadFile(
+          'https://services.gradle.org/distributions/gradle-5.3.1-bin.zip',
+          'C:\gradle-bin.zip'
+        )
+        [System.IO.Compression.ZipFile]::ExtractToDirectory("C:\gradle-bin.zip", "C:\gradle")
+      }
+  - cmd: SET PATH=C:\maven\apache-maven-3.2.5\bin;C:\gradle\gradle-5.3.1\bin;%JAVA_HOME%\bin;%PATH%
   - cmd: SET MAVEN_OPTS=-XX:MaxPermSize=2g -Xmx4g
   - cmd: SET JAVA_OPTS=-XX:MaxPermSize=2g -Xmx4g
   - cmd: SET M2_HOME=C:\maven\apache-maven-3.2.5
   - cmd: java -version
+  - cmd: gradle -v
+  - cmd: gradle -b modules\openapi-generator-gradle-plugin\samples\local-spec\build.gradle buildGoSdk --info
   - cmd: dir/w
   - git clone https://github.com/wing328/swagger-samples
   - ps: Start-Process -FilePath 'C:\maven\apache-maven-3.2.5\bin\mvn' -ArgumentList 'jetty:run' -WorkingDirectory "$env:appveyor_build_folder\swagger-samples\java\java-jersey-jaxrs-ci"
@@ -57,4 +69,5 @@ test_script:
 
 cache:
   - C:\maven\
+  - C:\gradle\
   - C:\Users\appveyor\.m2

modules/openapi-generator-gradle-plugin/samples/local-spec/gradle.properties

@@ -1 +1 @@
-openApiGeneratorVersion=3.3.4
+openApiGeneratorVersion=4.0.0-beta3