Refactor SubmitRequirementsJson into a separate class

So that we can reuse this logic with other callers later.

Change-Id: I7f1ec31b6e47f47439e758e03e83be1f9f2c077c
diff --git a/java/com/google/gerrit/server/change/ChangeJson.java b/java/com/google/gerrit/server/change/ChangeJson.java
index db25dc7..9a94d93 100644
--- a/java/com/google/gerrit/server/change/ChangeJson.java
+++ b/java/com/google/gerrit/server/change/ChangeJson.java
@@ -61,8 +61,6 @@
 import com.google.gerrit.entities.SubmitRecord;
 import com.google.gerrit.entities.SubmitRecord.Status;
 import com.google.gerrit.entities.SubmitRequirement;
-import com.google.gerrit.entities.SubmitRequirementExpression;
-import com.google.gerrit.entities.SubmitRequirementExpressionResult;
 import com.google.gerrit.entities.SubmitRequirementResult;
 import com.google.gerrit.entities.SubmitTypeRecord;
 import com.google.gerrit.exceptions.StorageException;
@@ -80,7 +78,6 @@
 import com.google.gerrit.extensions.common.ReviewerUpdateInfo;
 import com.google.gerrit.extensions.common.RevisionInfo;
 import com.google.gerrit.extensions.common.SubmitRecordInfo;
-import com.google.gerrit.extensions.common.SubmitRequirementExpressionInfo;
 import com.google.gerrit.extensions.common.SubmitRequirementResultInfo;
 import com.google.gerrit.extensions.common.TrackingIdInfo;
 import com.google.gerrit.extensions.restapi.Url;
@@ -378,11 +375,11 @@
     return submitRecordInfos;
   }
 
-  private static Collection<SubmitRequirementResultInfo> submitRequirementsFor(ChangeData cd) {
+  private Collection<SubmitRequirementResultInfo> submitRequirementsFor(ChangeData cd) {
     Collection<SubmitRequirementResultInfo> reqInfos = new ArrayList<>();
     Map<SubmitRequirement, SubmitRequirementResult> requirements = cd.submitRequirements();
     for (Map.Entry<SubmitRequirement, SubmitRequirementResult> entry : requirements.entrySet()) {
-      reqInfos.add(submitRequirementToInfo(entry.getKey(), entry.getValue()));
+      reqInfos.add(SubmitRequirementsJson.toInfo(entry.getKey(), entry.getValue()));
     }
     return reqInfos;
   }
@@ -420,39 +417,6 @@
     return info;
   }
 
-  private static SubmitRequirementResultInfo submitRequirementToInfo(
-      SubmitRequirement req, SubmitRequirementResult result) {
-    SubmitRequirementResultInfo info = new SubmitRequirementResultInfo();
-    info.name = req.name();
-    info.description = req.description().orElse(null);
-    if (req.applicabilityExpression().isPresent()) {
-      info.applicabilityExpressionResult =
-          submitRequirementExpressionToInfo(
-              req.applicabilityExpression().get(), result.applicabilityExpressionResult().get());
-    }
-    if (req.overrideExpression().isPresent()) {
-      info.overrideExpressionResult =
-          submitRequirementExpressionToInfo(
-              req.overrideExpression().get(), result.overrideExpressionResult().get());
-    }
-    info.submittabilityExpressionResult =
-        submitRequirementExpressionToInfo(
-            req.submittabilityExpression(), result.submittabilityExpressionResult());
-    info.status = SubmitRequirementResultInfo.Status.valueOf(result.status().toString());
-    info.isLegacy = result.legacy();
-    return info;
-  }
-
-  private static SubmitRequirementExpressionInfo submitRequirementExpressionToInfo(
-      SubmitRequirementExpression expression, SubmitRequirementExpressionResult result) {
-    SubmitRequirementExpressionInfo info = new SubmitRequirementExpressionInfo();
-    info.expression = expression.expressionString();
-    info.fulfilled = result.status().equals(SubmitRequirementExpressionResult.Status.PASS);
-    info.passingAtoms = result.passingAtoms();
-    info.failingAtoms = result.failingAtoms();
-    return info;
-  }
-
   private static void finish(ChangeInfo info) {
     info.id =
         Joiner.on('~')
diff --git a/java/com/google/gerrit/server/change/SubmitRequirementsJson.java b/java/com/google/gerrit/server/change/SubmitRequirementsJson.java
new file mode 100644
index 0000000..ebb0790
--- /dev/null
+++ b/java/com/google/gerrit/server/change/SubmitRequirementsJson.java
@@ -0,0 +1,63 @@
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed 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 com.google.gerrit.server.change;
+
+import com.google.gerrit.entities.SubmitRequirement;
+import com.google.gerrit.entities.SubmitRequirementExpression;
+import com.google.gerrit.entities.SubmitRequirementExpressionResult;
+import com.google.gerrit.entities.SubmitRequirementResult;
+import com.google.gerrit.extensions.common.SubmitRequirementExpressionInfo;
+import com.google.gerrit.extensions.common.SubmitRequirementResultInfo;
+
+/**
+ * Produces submit requirements related entities like {@link SubmitRequirementResultInfo}s, which
+ * are serialized to JSON afterwards.
+ */
+public class SubmitRequirementsJson {
+  private SubmitRequirementsJson() {}
+
+  public static SubmitRequirementResultInfo toInfo(
+      SubmitRequirement req, SubmitRequirementResult result) {
+    SubmitRequirementResultInfo info = new SubmitRequirementResultInfo();
+    info.name = req.name();
+    info.description = req.description().orElse(null);
+    if (req.applicabilityExpression().isPresent()) {
+      info.applicabilityExpressionResult =
+          submitRequirementExpressionToInfo(
+              req.applicabilityExpression().get(), result.applicabilityExpressionResult().get());
+    }
+    if (req.overrideExpression().isPresent()) {
+      info.overrideExpressionResult =
+          submitRequirementExpressionToInfo(
+              req.overrideExpression().get(), result.overrideExpressionResult().get());
+    }
+    info.submittabilityExpressionResult =
+        submitRequirementExpressionToInfo(
+            req.submittabilityExpression(), result.submittabilityExpressionResult());
+    info.status = SubmitRequirementResultInfo.Status.valueOf(result.status().toString());
+    info.isLegacy = result.legacy();
+    return info;
+  }
+
+  private static SubmitRequirementExpressionInfo submitRequirementExpressionToInfo(
+      SubmitRequirementExpression expression, SubmitRequirementExpressionResult result) {
+    SubmitRequirementExpressionInfo info = new SubmitRequirementExpressionInfo();
+    info.expression = expression.expressionString();
+    info.fulfilled = result.status().equals(SubmitRequirementExpressionResult.Status.PASS);
+    info.passingAtoms = result.passingAtoms();
+    info.failingAtoms = result.failingAtoms();
+    return info;
+  }
+}