title: launchBillingFlow() couldn't display the Google Play purchase screen
body: <p>I'm using Google Play Billing Library in my app. App relase in internal test relase type. But when I clicked product button, launchBillingFlow() couldn't display the Google Play purchase screen.After click, code follows directly "//DO SOMETHING AND RETURN MENU OPERATIONS" part of block. 
  My apps config lines: firstly in my manifest has a "com.android.vending.BILLING". Secondly; my gradle files has a current version of billing library; "implementation 'com.android.billingclient:billing:2.0.3'". But I dont know why still couldn't display purchase screen.
   My code is as follows;</p>
  
  <pre><code> import android.content.Intent;
  import android.content.SharedPreferences;
  
  import androidx.annotation.Nullable;
  import androidx.appcompat.app.AppCompatActivity;
  import android.os.Bundle;
  import android.view.View;
  import android.view.Window;
  import android.view.WindowManager;
  import android.widget.Button;
  import android.widget.Toast;
  
  import com.android.billingclient.api.BillingClient;
  import com.android.billingclient.api.BillingClientStateListener;
  import com.android.billingclient.api.BillingFlowParams;
  import com.android.billingclient.api.BillingResult;
  import com.android.billingclient.api.Purchase;
  import com.android.billingclient.api.PurchaseHistoryResponseListener;
  import com.android.billingclient.api.PurchasesUpdatedListener;
  import com.android.billingclient.api.SkuDetails;
  import com.android.billingclient.api.SkuDetailsParams;
  import com.android.billingclient.api.SkuDetailsResponseListener;
  import com.ynapp.yesornoapp.R;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.List;
  
  public class MyProductActivity extends AppCompatActivity  implements PurchasesUpdatedListener {
      //PREMIUM PRODUCTS
      Button btProduct;
      public static final String PR_PREFS_PRODUCT_ONE = "ProductOne";
      SharedPreferences prefs_product_one;
      //Will be used for in-app purchases.
      List&lt;SkuDetails&gt; skuDetailsList;
      BillingClient billingClient;
      Intent itMain;
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          requestWindowFeature(Window.FEATURE_NO_TITLE);
          getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                  WindowManager.LayoutParams.FLAG_FULLSCREEN);
          themeUtils.onActivityCreateSetTheme(this);
          setContentView(R.layout.activity_my_product);
          setupBillingClient();
          btProduct = (Button)findViewById(R.id.buttonforest);
      }
  
      public void onClickTheme(View view){
          SharedPreferences sharedPref = getSharedPreferences("MyData",MODE_PRIVATE);//MODE_PRIVATE
          final SharedPreferences.Editor editor = sharedPref.edit();
          switch (view.getId()){
              case R.id.buttonproductone:
                  //önceden ödeme yapılıp yapılmadığını sorguluyoruz
                  prefs_product_one= getSharedPreferences(PR_PREFS_PRODUCT_ONE,MODE_PRIVATE);
                  final int product_one_flag = prefs_product_one.getInt("productone",0);
                  List&lt;String&gt; skuList = new ArrayList&lt;&gt;();
                  skuList.add("purch_product_one");
  
                  if(billingClient.isReady() &amp;&amp; product_one_flag==0){
                      SkuDetailsParams.Builder params = SkuDetailsParams.newBuilder();
                      params.setSkusList(skuList).setType(BillingClient.SkuType.INAPP).build();
  
                      billingClient.querySkuDetailsAsync(params.build(), new SkuDetailsResponseListener() {
                          @Override
                          public void onSkuDetailsResponse(BillingResult billingResult, List&lt;SkuDetails&gt; skuDetailsList) {
                              if(billingResult.getResponseCode() == BillingClient.BillingResponseCode.OK &amp;&amp;
                              skuDetailsList != null){
                                  for(SkuDetails skuDetails: skuDetailsList){
                                      String sku = skuDetails.getSku();
                                      String price = skuDetails.getPrice();
                                      if("prefs_product_one".equals(sku)){
                                          Toast.makeText(MyProductActivity.this, sku + ": " + price, Toast.LENGTH_SHORT).show();
                                          BillingFlowParams flowParams = BillingFlowParams.newBuilder()
                                                  .setSkuDetails(skuDetails)
                                                  .build();
                                          BillingResult billingResponseCode = billingClient.launchBillingFlow(MyProductActivity.this, flowParams);
                                          if (billingResponseCode.getResponseCode() == BillingClient.BillingResponseCode.OK) {
                                              //DO SOMETHING AND RETURN MENU OPERATIONS
                                          }
                                      }
                                  }
                              }
  
                          }
  
                      });
                  }
                  else{
                      if(product_one_flag ==0)
                          Toast.makeText(MyProductActivity.this, "Cannot query product", Toast.LENGTH_SHORT).show();
                      else{
                          Toast.makeText(getApplicationContext(),btProduct.getText().toString(),Toast.LENGTH_SHORT).show();
                      }
                  }
                  break;
          }
      }
  
      public  void setupBillingClient(){
          billingClient = BillingClient.newBuilder(this).enablePendingPurchases().setListener(this).build();
          billingClient.startConnection(new BillingClientStateListener() {
              @Override
              public void onBillingSetupFinished(BillingResult billingResult) {
                  if (billingResult.getResponseCode() == BillingClient.BillingResponseCode.OK) {
  
                      Toast.makeText(MyProductActivity.this, "Success to connect Billing", Toast.LENGTH_SHORT).show();
                  }
              }
              @Override
              public void onBillingServiceDisconnected() {
  
              }
          });
      }
  
  
      @Override
      public void onPurchasesUpdated(BillingResult billingResult, @Nullable List&lt;Purchase&gt; purchases) {
  
      }
  }
  </code></pre>