feat: SDK-1568 expose okhttp client as a configuration for XAP sdk

Author: dtayeh

customizations/generator/openapi/src/main/resources/templates/expediagroup-sdk/client.mustache

@@ -26,8 +26,23 @@ class {{clientClassname}}Client private constructor(clientConfiguration: XapClie
         )
     }
 
+    class BuilderWithHttpClient() : BaseXapClient.BuilderWithHttpClient<BuilderWithHttpClient>() {
+        override fun build() : {{clientClassname}}Client {
+
+        if (okHttpClient == null) {
+            throw ExpediaGroupConfigurationException(getMissingRequiredConfigurationMessage(ConfigurationName.OKHTTP_CLIENT))
+        }
+
+        return {{clientClassname}}Client(
+                XapClientConfiguration(key, secret, endpoint, null, null, null, maskedLoggingHeaders, maskedLoggingBodyFields, okHttpClient)
+            )
+        }
+    }
+
     companion object {
         @JvmStatic fun builder() = Builder()
+
+        @JvmStatic fun builderWithHttpClient() = BuilderWithHttpClient()
     }
 
     override suspend fun throwServiceException(response: HttpResponse, operationId: String) {

customizations/generator/openapi/src/main/resources/templates/expediagroup-sdk/imports/core.mustache

@@ -1,7 +1,10 @@
 import com.expediagroup.sdk.core.client.BaseXapClient
 import com.expediagroup.sdk.core.configuration.XapClientConfiguration
+import com.expediagroup.sdk.core.constant.ConfigurationName
 import com.expediagroup.sdk.core.constant.HeaderKey
+import com.expediagroup.sdk.core.constant.provider.ExceptionMessageProvider.getMissingRequiredConfigurationMessage
 import com.expediagroup.sdk.core.model.exception.ExpediaGroupException
+import com.expediagroup.sdk.core.model.exception.client.ExpediaGroupConfigurationException
 import com.expediagroup.sdk.core.model.exception.service.ExpediaGroupServiceException
 import com.expediagroup.sdk.core.model.exception.handle
 import com.expediagroup.sdk.core.model.paging.Paginator