Update deprecated api (#411)

* - update gradle version 3.1.0
- remove Warning:Configuration 'compile' replaced with 'implementation'
- update targetSdkVersion 26 (Google Play requires that apps target API level 26 or higher)
- remove IInAppBillingService.aidl file and Use the Google Play Billing Library
- update deprecated API

* sample project use annotations version 26.0.1

* revert compileSdkVersion and buildToolsVersion

* revert gradle version

Author: Jin Wooram Seo

build.gradle

@@ -3,6 +3,10 @@ buildscript {
     repositories {
         mavenCentral()
         jcenter()
+        maven {
+            url 'https://maven.google.com/'
+            name 'Google'
+        }
     }
     dependencies {
         classpath 'com.android.tools.build:gradle:2.3.3'
@@ -15,6 +19,11 @@ allprojects {
 
     repositories {
         mavenCentral()
+        jcenter()
+        maven {
+            url 'https://maven.google.com/'
+            name 'Google'
+        }
     }
 
     sourceSets {

gradle/wrapper/gradle-wrapper.properties

@@ -1,4 +1,4 @@
-#Wed Mar 15 08:51:52 MSK 2017
+#Wed Jul 03 11:27:59 KST 2019
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME

library/build.gradle

@@ -36,6 +36,7 @@ dependencies {
     androidTestCompile 'com.android.support.test:runner:0.5'
     androidTestCompile 'com.android.support.test:rules:0.5'
     compile 'com.android.support:support-annotations:25.3.1'
+    compile 'com.android.billingclient:billing:2.0.1'
 }
 
 configurations.archives.extendsFrom configurations.default

library/src/main/aidl/com/android/vending/billing/IInAppBillingService.aidl

@@ -782,11 +782,11 @@ public boolean consumePurchase(String productId)
 		try
 		{
 			TransactionDetails transaction = getPurchaseTransactionDetails(productId, cachedProducts);
-			if (transaction != null && !TextUtils.isEmpty(transaction.purchaseToken))
+			if (transaction != null && !TextUtils.isEmpty(transaction.purchaseInfo.purchaseData.purchaseToken))
 			{
 				int response = billingService.consumePurchase(Constants.GOOGLE_API_VERSION,
 															  contextPackageName,
-															  transaction.purchaseToken);
+															  transaction.purchaseInfo.purchaseData.purchaseToken);
 				if (response == Constants.BILLING_RESPONSE_RESULT_OK)
 				{
 					cachedProducts.remove(productId);
@@ -988,7 +988,7 @@ private boolean verifyPurchaseSignature(String productId, String purchaseData, S
 
 	public boolean isValidTransactionDetails(TransactionDetails transactionDetails)
 	{
-		return verifyPurchaseSignature(transactionDetails.productId,
+		return verifyPurchaseSignature(transactionDetails.purchaseInfo.purchaseData.productId,
 									   transactionDetails.purchaseInfo.responseData,
 									   transactionDetails.purchaseInfo.signature) &&
 			   checkMerchant(transactionDetails);