AbstractElasticIndex: Add helper method to invoke base64 decode

Change-Id: I133b607b1af0ce7d8f770585870ffc3e2ae79b15
diff --git a/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java b/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
index 2af6508..d634e35 100644
--- a/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
+++ b/java/com/google/gerrit/elasticsearch/AbstractElasticIndex.java
@@ -17,7 +17,6 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.gson.FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES;
 import static java.nio.charset.StandardCharsets.UTF_8;
-import static org.apache.commons.codec.binary.Base64.decodeBase64;
 
 import com.google.common.collect.ArrayListMultimap;
 import com.google.common.collect.FluentIterable;
@@ -84,6 +83,10 @@
   protected static final String SEARCH = "_search";
   protected static final String SETTINGS = "settings";
 
+  protected static byte[] decodeBase64(String base64String) {
+    return Base64.decodeBase64(base64String);
+  }
+
   protected static <T> List<T> decodeProtos(
       JsonObject doc, String fieldName, ProtobufCodec<T> codec) {
     JsonArray field = doc.getAsJsonArray(fieldName);
diff --git a/java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java b/java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java
index eabe6ba..9466816 100644
--- a/java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java
+++ b/java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java
@@ -21,7 +21,6 @@
 import static com.google.gerrit.server.index.change.ChangeIndexRewriter.OPEN_STATUSES;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.Objects.requireNonNull;
-import static org.apache.commons.codec.binary.Base64.decodeBase64;
 
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableListMultimap;