[Kotlin][Client] Add option to make all api method return a nullable model (#4422)

* Added new additional parameter to allow nullable api return types

* Tweaking samples and .bat files

I've added new .bat files for the kotlin-client to alllow windows-devs to re-generate required samples via windows-shell (for CI).

Author: Mordag

bin/kotlin-client-all.sh

@@ -7,3 +7,4 @@
 ./bin/kotlin-client-petstore.sh
 ./bin/kotlin-client-string.sh
 ./bin/kotlin-client-threetenbp.sh
+./bin/kotlin-client-nullable.sh

bin/kotlin-client-nullable.sh

@@ -0,0 +1,32 @@
+#!/bin/sh
+
+SCRIPT="$0"
+echo "# START SCRIPT: $SCRIPT"
+
+while [ -h "$SCRIPT" ] ; do
+  ls=$(ls -ld "$SCRIPT")
+  link=$(expr "$ls" : '.*-> \(.*\)$')
+  if expr "$link" : '/.*' > /dev/null; then
+    SCRIPT="$link"
+  else
+    SCRIPT=$(dirname "$SCRIPT")/"$link"
+  fi
+done
+
+if [ ! -d "${APP_DIR}" ]; then
+  APP_DIR=$(dirname "$SCRIPT")/..
+  APP_DIR=$(cd "${APP_DIR}"; pwd)
+fi
+
+executable="./modules/openapi-generator-cli/target/openapi-generator-cli.jar"
+
+if [ ! -f "$executable" ]
+then
+  mvn -B clean package
+fi
+
+# if you've executed sbt assembly previously it will use that instead.
+export JAVA_OPTS="${JAVA_OPTS} -Xmx1024M -DloggerPath=conf/log4j.properties"
+ags="generate -t modules/openapi-generator/src/main/resources/kotlin-client -i modules/openapi-generator/src/test/resources/2_0/petstore.yaml -g kotlin --artifact-id kotlin-petstore-nullable --additional-properties nullableReturnType=true,serializableModel=true -o samples/client/petstore/kotlin-nullable $@"
+
+java ${JAVA_OPTS} -jar ${executable} ${ags}

bin/windows/kotlin-client-all.bat

@@ -0,0 +1,8 @@
+call powershell -command "& '%~dp0\kotlin-client-gson.bat'"
+call powershell -command "& '%~dp0\kotlin-client-nonpublic.bat'"
+call powershell -command "& '%~dp0\kotlin-client-okhttp3.bat'"
+call powershell -command "& '%~dp0\kotlin-client-petstore-multiplatform.bat'"
+call powershell -command "& '%~dp0\kotlin-client-petstore.bat'"
+call powershell -command "& '%~dp0\kotlin-client-string.bat'"
+call powershell -command "& '%~dp0\kotlin-client-threetenbp.bat'"
+call powershell -command "& '%~dp0\kotlin-client-nullable.bat'"

bin/windows/kotlin-client-nullable.bat

@@ -0,0 +1,10 @@
+set executable=.\modules\openapi-generator-cli\target\openapi-generator-cli.jar
+
+If Not Exist %executable% (
+  mvn clean package
+)
+
+REM set JAVA_OPTS=%JAVA_OPTS% -Xmx1024M -DloggerPath=conf/log4j.properties
+set ags=generate -i modules\openapi-generator\src\test\resources\2_0\petstore.yaml -g kotlin --artifact-id "kotlin-petstore-nullable" --additional-properties nullableReturnType=true,serializableModel=true -o samples\client\petstore\kotlin-nullable
+
+java %JAVA_OPTS% -jar %executable% %ags%

bin/windows/kotlin-client-petstore.bat

@@ -5,6 +5,6 @@ If Not Exist %executable% (
 )
 
 REM set JAVA_OPTS=%JAVA_OPTS% -Xmx1024M -DloggerPath=conf/log4j.properties
-set ags=generate  --artifact-id "kotlin-petstore-client" -i modules\openapi-generator\src\test\resources\2_0\petstore.yaml -g kotlin -o samples\client\petstore\kotlin
+set ags=generate  --artifact-id "kotlin-petstore-client" -i modules\openapi-generator\src\test\resources\2_0\petstore.yaml -g kotlin -o samples\client\petstore\kotlin --additional-properties dateLibrary=java8,serializableModel=true
 
 java %JAVA_OPTS% -jar %executable% %ags%

bin/windows/kotlin-client-string.bat

@@ -0,0 +1,10 @@
+set executable=.\modules\openapi-generator-cli\target\openapi-generator-cli.jar
+
+If Not Exist %executable% (
+  mvn clean package
+)
+
+REM set JAVA_OPTS=%JAVA_OPTS% -Xmx1024M -DloggerPath=conf/log4j.properties
+set ags=generate -i modules\openapi-generator\src\test\resources\2_0\petstore.yaml -g kotlin --artifact-id "kotlin-petstore-string" --additional-properties dateLibrary=string,serializableModel=true -o samples\client\petstore\kotlin-string
+
+java %JAVA_OPTS% -jar %executable% %ags%

bin/windows/kotlin-client-threetenbp.bat

@@ -0,0 +1,10 @@
+set executable=.\modules\openapi-generator-cli\target\openapi-generator-cli.jar
+
+If Not Exist %executable% (
+  mvn clean package
+)
+
+REM set JAVA_OPTS=%JAVA_OPTS% -Xmx1024M -DloggerPath=conf/log4j.properties
+set ags=generate -i modules\openapi-generator\src\test\resources\2_0\petstore.yaml -g kotlin --artifact-id "kotlin-petstore-threetenbp" --additional-properties dateLibrary=threetenbp -o samples\client\petstore\kotlin-threetenbp
+
+java %JAVA_OPTS% -jar %executable% %ags%

modules/openapi-generator/src/main/resources/kotlin-client/api.mustache

@@ -24,14 +24,14 @@ import {{packageName}}.infrastructure.toMultiValue
     * {{summary}}
     * {{notes}}
     {{#allParams}}* @param {{paramName}} {{description}} {{^required}}(optional{{#defaultValue}}, default to {{{.}}}{{/defaultValue}}){{/required}}
-    {{/allParams}}* @return {{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}void{{/returnType}}
+    {{/allParams}}* @return {{#returnType}}{{{returnType}}}{{#nullableReturnType}} or null{{/nullableReturnType}}{{/returnType}}{{^returnType}}void{{/returnType}}
     * @throws UnsupportedOperationException If the API returns an informational or redirection response
     * @throws ClientException If the API returns a client error response
     * @throws ServerException If the API returns a server error response
     */{{#returnType}}
     @Suppress("UNCHECKED_CAST"){{/returnType}}
     @Throws(UnsupportedOperationException::class, ClientException::class, ServerException::class)
-    fun {{operationId}}({{#allParams}}{{paramName}}: {{{dataType}}}{{^required}}?{{/required}}{{#hasMore}}, {{/hasMore}}{{/allParams}}) : {{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}Unit{{/returnType}} {
+    fun {{operationId}}({{#allParams}}{{paramName}}: {{{dataType}}}{{^required}}?{{/required}}{{#hasMore}}, {{/hasMore}}{{/allParams}}) : {{#returnType}}{{{returnType}}}{{#nullableReturnType}}?{{/nullableReturnType}}{{/returnType}}{{^returnType}}Unit{{/returnType}} {
         val localVariableBody: kotlin.Any? = {{#hasBodyParam}}{{#bodyParams}}{{paramName}}{{/bodyParams}}{{/hasBodyParam}}{{^hasBodyParam}}{{^hasFormParams}}null{{/hasFormParams}}{{#hasFormParams}}mapOf({{#formParams}}"{{{baseName}}}" to "${{paramName}}"{{#hasMore}}, {{/hasMore}}{{/formParams}}){{/hasFormParams}}{{/hasBodyParam}}
         val localVariableQuery: MultiValueMap = {{^hasQueryParams}}mutableMapOf()
 {{/hasQueryParams}}{{#hasQueryParams}}mutableMapOf<kotlin.String, List<kotlin.String>>()
@@ -68,7 +68,7 @@ import {{packageName}}.infrastructure.toMultiValue
         )
 
         return when (localVarResponse.responseType) {
-            ResponseType.Success -> {{#returnType}}(localVarResponse as Success<*>).data as {{{returnType}}}{{/returnType}}{{^returnType}}Unit{{/returnType}}
+            ResponseType.Success -> {{#returnType}}(localVarResponse as Success<*>).data as {{{returnType}}}{{#nullableReturnType}}?{{/nullableReturnType}}{{/returnType}}{{^returnType}}Unit{{/returnType}}
             ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> throw ClientException((localVarResponse as ClientError<*>).body as? String ?: "Client error")

modules/openapi-generator/src/main/resources/kotlin-client/api_doc.mustache

@@ -30,7 +30,7 @@ val apiInstance = {{{classname}}}()
 val {{{paramName}}} : {{{dataType}}} = {{{example}}} // {{{dataType}}} | {{{description}}}
 {{/allParams}}
 try {
-    {{#returnType}}val result : {{{returnType}}} = {{/returnType}}apiInstance.{{{operationId}}}({{#allParams}}{{{paramName}}}{{#hasMore}}, {{/hasMore}}{{/allParams}}){{#returnType}}
+    {{#returnType}}val result : {{{returnType}}}{{#nullableReturnType}}?{{/nullableReturnType}} = {{/returnType}}apiInstance.{{{operationId}}}({{#allParams}}{{{paramName}}}{{#hasMore}}, {{/hasMore}}{{/allParams}}){{#returnType}}
     println(result){{/returnType}}
 } catch (e: ClientException) {
     println("4xx response calling {{{classname}}}#{{{operationId}}}")

modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm/infrastructure/ApiInfrastructureResponse.kt.mustache

@@ -10,7 +10,7 @@ package {{packageName}}.infrastructure
 }
 
 {{#nonPublicApi}}internal {{/nonPublicApi}}class Success<T>(
-    val data: T,
+    val data: T{{#nullableReturnType}}?{{/nullableReturnType}},
     override val statusCode: Int = -1,
     override val headers: Map<String, List<String>> = mapOf()
 ): ApiInfrastructureResponse<T>(ResponseType.Success)