Support consistency with existing KB invoice items where tierDetails …

…is presented

pom.xml

@@ -41,6 +41,7 @@
     <properties>
         <check.spotbugs-exclude-filter-file>spotbugs-exclude.xml</check.spotbugs-exclude-filter-file>
         <jooq.version>3.14.15</jooq.version>
+        <killbill.version>0.22.32</killbill.version>
         <osgi.private>org.killbill.billing.plugin.vertex.*</osgi.private>
     </properties>
     <dependencies>
@@ -155,6 +156,11 @@
             <artifactId>killbill-api</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>org.kill-bill.billing</groupId>
+            <artifactId>killbill-invoice</artifactId>
+            <scope>provided</scope>
+        </dependency>
         <dependency>
             <groupId>org.kill-bill.billing</groupId>
             <artifactId>killbill-platform-osgi-api</artifactId>

src/main/java/org/killbill/billing/plugin/vertex/TaxItemDetails.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2020-2024 Equinix, Inc
+ * Copyright 2020-2024 The Billing Project, LLC
+ *
+ * The Billing Project licenses this file to you under the Apache License, version 2.0
+ * (the "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at:
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.killbill.billing.plugin.vertex;
+
+import java.math.BigDecimal;
+import java.util.List;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+import org.killbill.billing.invoice.usage.details.UsageConsumableInArrearAggregate;
+import org.killbill.billing.invoice.usage.details.UsageConsumableInArrearTierUnitAggregate;
+
+/**
+ * Wrapper to add taxRate details into itemDetails
+ */
+public class TaxItemDetails {
+
+    private final UsageConsumableInArrearAggregate usageDetail;
+    private final Double taxRate;
+
+    public TaxItemDetails(@Nonnull final Double taxRate, @Nullable final UsageConsumableInArrearAggregate usageDetail) {
+        this.usageDetail = usageDetail;
+        this.taxRate = taxRate;
+    }
+
+    public List<UsageConsumableInArrearTierUnitAggregate> getTierDetails() {
+        return usageDetail != null ? usageDetail.getTierDetails() : null;
+    }
+
+    public BigDecimal getAmount() {
+        return usageDetail != null ? usageDetail.getAmount() : null;
+    }
+
+    public Double getTaxRate() {
+        return taxRate;
+    }
+}

src/main/java/org/killbill/billing/plugin/vertex/VertexTaxCalculator.java

@@ -37,6 +37,7 @@
 import org.killbill.billing.account.api.Account;
 import org.killbill.billing.invoice.api.Invoice;
 import org.killbill.billing.invoice.api.InvoiceItem;
+import org.killbill.billing.invoice.usage.details.UsageConsumableInArrearAggregate;
 import org.killbill.billing.osgi.libs.killbill.OSGIKillbillAPI;
 import org.killbill.billing.payment.api.PluginProperty;
 import org.killbill.billing.plugin.api.PluginProperties;
@@ -68,13 +69,14 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import com.fasterxml.jackson.annotation.JsonInclude.Include;
 import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.HashMultimap;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Multimap;
 
 public class VertexTaxCalculator extends PluginTaxCalculator {
@@ -116,7 +118,7 @@ public VertexTaxCalculator(final VertexApiConfigurationHandler vertexApiConfigur
         this.vertexApiConfigurationHandler = vertexApiConfigurationHandler;
         this.clock = clock;
         this.dao = dao;
-        this.objectMapper = new ObjectMapper();
+        this.objectMapper = new ObjectMapper().setSerializationInclusion(Include.NON_NULL);
     }
 
     public List<InvoiceItem> compute(final Account account,
@@ -325,7 +327,10 @@ private InvoiceItem createTaxInvoiceItem(final InvoiceItem taxableItem, final UU
             taxRate = calculatedTax.divide(taxableItem.getAmount(), 5, RoundingMode.FLOOR).doubleValue();
         }
 
-        final String taxItemDetails = createTaxItemDetails(ImmutableMap.of("taxRate", taxRate));
+        final UsageConsumableInArrearAggregate usageDetail = getUsageDetailFromItemDetails(taxItem);
+
+        final String taxItemDetails = createTaxItemDetails(new TaxItemDetails(taxRate, usageDetail));
+
         if (taxItemDetails == null) {
             return taxItem;
         }
@@ -361,7 +366,22 @@ private InvoiceItem createTaxInvoiceItem(final InvoiceItem taxableItem, final UU
                                              .validate().build());
     }
 
-    private String createTaxItemDetails(@Nonnull final Map<String, Object> taxItemDetails) {
+    private UsageConsumableInArrearAggregate getUsageDetailFromItemDetails(final InvoiceItem taxItem) {
+        if (taxItem.getItemDetails() == null) {
+            return null;
+        }
+
+        UsageConsumableInArrearAggregate usageDetail = null;
+        try {
+            usageDetail = objectMapper.readValue(taxItem.getItemDetails(), new TypeReference<UsageConsumableInArrearAggregate>() {});
+        } catch (JsonProcessingException e) {
+            logger.error("Failed to parse the item details for tax item with ID: {}", taxItem.getId(), e);
+        }
+
+        return usageDetail;
+    }
+
+    private String createTaxItemDetails(@Nonnull final TaxItemDetails taxItemDetails) {
         try {
             return objectMapper.writeValueAsString(taxItemDetails);
         } catch (JsonProcessingException exception) {