Do not deserialize value when it is String When the Zookeeper value is already a String, there is no need to perform any deserialization. Change-Id: Ibb53360973328e3dd435a92ae8548eb1393378b3

diff --git a/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/IdentityDeserializer.java b/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/IdentityDeserializer.java
new file mode 100644
index 0000000..ddaec82
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/IdentityDeserializer.java

@@ -0,0 +1,28 @@
+// Copyright (C) 2020 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.googlesource.gerrit.plugins.validation.dfsrefdb.zookeeper;
+
+public class IdentityDeserializer implements StringDeserializer<String> {
+
+  @Override
+  public Class<String> getTypeClass() {
+    return String.class;
+  }
+
+  @Override
+  public String fromString(String str) {
+    return str;
+  }
+}

diff --git a/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/StringDeserializerFactory.java b/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/StringDeserializerFactory.java
index e7f01df..93b2f95 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/StringDeserializerFactory.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/StringDeserializerFactory.java

@@ -26,10 +26,11 @@
     this.stringToGenericDeserializers = stringToGenericDeserializers;
   }
 
-  public StringDeserializer create(final Class clazz) throws DeserializerException {
-    for (StringDeserializer stringDeserializer : stringToGenericDeserializers) {
+  @SuppressWarnings("unchecked")
+  public <T> StringDeserializer<T> create(final Class<T> clazz) throws DeserializerException {
+    for (StringDeserializer<?> stringDeserializer : stringToGenericDeserializers) {
       if (stringDeserializer.getTypeClass().getName().equals(clazz.getTypeName())) {
-        return stringDeserializer;
+        return (StringDeserializer<T>) stringDeserializer;
       }
     }
     throw new DeserializerException("No serializer registered for class " + clazz.getName());

diff --git a/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkSharedRefDatabase.java b/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkSharedRefDatabase.java
index 6ec3949..19257c3 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkSharedRefDatabase.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkSharedRefDatabase.java

@@ -147,6 +147,7 @@
     }
   }
 
+  @Override
   public <T> boolean compareAndPut(
       Project.NameKey project, String refName, T expectedValue, T newValue)
       throws GlobalRefDbSystemError {

diff --git a/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkValidationModule.java b/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkValidationModule.java
index ddd5398..cf97adf 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkValidationModule.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkValidationModule.java

@@ -54,5 +54,8 @@
     DynamicSet.bind(binder(), StringDeserializer.class)
         .to(StringToObjectIdDeserializer.class)
         .in(Scopes.SINGLETON);
+    DynamicSet.bind(binder(), StringDeserializer.class)
+        .to(IdentityDeserializer.class)
+        .in(Scopes.SINGLETON);
   }
 }

diff --git a/src/test/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkSharedRefDatabaseTest.java b/src/test/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkSharedRefDatabaseTest.java
index f019e60..aa7f748 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkSharedRefDatabaseTest.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkSharedRefDatabaseTest.java

@@ -44,6 +44,7 @@
     result.add("zookeeper", new StringToLongDeserializer());
     result.add("zookeeper", new StringToIntDeserializer());
     result.add("zookeeper", new StringToObjectIdDeserializer());
+    result.add("zookeeper", new IdentityDeserializer());
     return result;
   }
 
@@ -217,6 +218,19 @@
   }
 
   @Test
+  public void shouldReturnStringValueIfExists() throws Exception {
+    zkSharedRefDatabase.compareAndPut(A_TEST_PROJECT_NAME_KEY, A_TEST_REF_NAME, null, "foo");
+    assertThat(
+            zkSharedRefDatabase
+                .get(A_TEST_PROJECT_NAME_KEY, A_TEST_REF_NAME, String.class)
+                .isPresent())
+        .isTrue();
+    assertThat(
+            zkSharedRefDatabase.<String>get(A_TEST_PROJECT_NAME_KEY, A_TEST_REF_NAME, String.class))
+        .isEqualTo(Optional.of("foo"));
+  }
+
+  @Test
   public void shouldReturnObjectIdValueIfExists() throws Exception {
     Ref ref = refOf(AN_OBJECT_ID_1);