Plugin API: Add method for adding reviewers with string as argument

This change simplifies adding reviewers.

Change-Id: I5ec0b5d22f7f3a41fbadf889e8b4c82be5a52e5c
diff --git a/gerrit-extension-api/src/main/java/com/google/gerrit/extensions/api/changes/ChangeApi.java b/gerrit-extension-api/src/main/java/com/google/gerrit/extensions/api/changes/ChangeApi.java
index 9aa9d48..e28c424 100644
--- a/gerrit-extension-api/src/main/java/com/google/gerrit/extensions/api/changes/ChangeApi.java
+++ b/gerrit-extension-api/src/main/java/com/google/gerrit/extensions/api/changes/ChangeApi.java
@@ -33,4 +33,5 @@
   ChangeApi revert(RevertInput in) throws RestApiException;
 
   void addReviewer(AddReviewerInput in) throws RestApiException;
+  void addReviewer(String in) throws RestApiException;
 }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/api/changes/ChangeApiImpl.java b/gerrit-server/src/main/java/com/google/gerrit/server/api/changes/ChangeApiImpl.java
index bb231e6..64d8172 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/api/changes/ChangeApiImpl.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/api/changes/ChangeApiImpl.java
@@ -138,6 +138,13 @@
   }
 
   @Override
+  public void addReviewer(String reviewer) throws RestApiException {
+    AddReviewerInput in = new AddReviewerInput();
+    in.reviewer = reviewer;
+    addReviewer(in);
+  }
+
+  @Override
   public void addReviewer(AddReviewerInput in) throws RestApiException {
     try {
       postReviewers.get().apply(change, in);