[kotlin][client] bytearray conversion (#2166)

* use kotlin.String for ByteArray fields (type: string, format: byte)

* revert "use kotlin.String for ByteArray fields (type: string, format: byte)"

* add ByteArrayAdapter for string <-> ByteArray conversion with moshi

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java

@@ -164,5 +164,6 @@ public class KotlinClientCodegen extends AbstractKotlinCodegen {
         supportingFiles.add(new SupportingFile("infrastructure/ResponseExtensions.kt.mustache", infrastructureFolder, "ResponseExtensions.kt"));
         supportingFiles.add(new SupportingFile("infrastructure/Serializer.kt.mustache", infrastructureFolder, "Serializer.kt"));
         supportingFiles.add(new SupportingFile("infrastructure/Errors.kt.mustache", infrastructureFolder, "Errors.kt"));
+        supportingFiles.add(new SupportingFile("infrastructure/ByteArrayAdapter.kt.mustache", infrastructureFolder, "ByteArrayAdapter.kt"));
     }
 }

modules/openapi-generator/src/main/resources/kotlin-client/infrastructure/ApiClient.kt.mustache

@@ -60,7 +60,9 @@ open class ApiClient(val baseUrl: String) {
                     fun toJson(uuid: UUID) = uuid.toString()
                     @FromJson
                     fun fromJson(s: String) = UUID.fromString(s)
-                }).build().adapter(T::class.java).fromJson(body.source())
+                })
+                .add(ByteArrayAdapter())
+                .build().adapter(T::class.java).fromJson(body.source())
             else -> TODO()
         }
     }

modules/openapi-generator/src/main/resources/kotlin-client/infrastructure/ByteArrayAdapter.kt.mustache

@@ -0,0 +1,12 @@
+package {{packageName}}.infrastructure
+
+import com.squareup.moshi.FromJson
+import com.squareup.moshi.ToJson
+
+class ByteArrayAdapter {
+    @ToJson
+    fun toJson(data: ByteArray): String = String(data)
+
+    @FromJson
+    fun fromJson(data: String): ByteArray = data.toByteArray()
+}

samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt

@@ -60,7 +60,9 @@ open class ApiClient(val baseUrl: String) {
                     fun toJson(uuid: UUID) = uuid.toString()
                     @FromJson
                     fun fromJson(s: String) = UUID.fromString(s)
-                }).build().adapter(T::class.java).fromJson(body.source())
+                })
+                .add(ByteArrayAdapter())
+                .build().adapter(T::class.java).fromJson(body.source())
             else -> TODO()
         }
     }

samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/infrastructure/ByteArrayAdapter.kt

@@ -0,0 +1,12 @@
+package org.openapitools.client.infrastructure
+
+import com.squareup.moshi.FromJson
+import com.squareup.moshi.ToJson
+
+class ByteArrayAdapter {
+    @ToJson
+    fun toJson(data: ByteArray): String = String(data)
+
+    @FromJson
+    fun fromJson(data: String): ByteArray = data.toByteArray()
+}