Adds group suggestions into ListGroups REST API.

This is a different approach of
Ie86de1f73ccd7bdec041730d95301d6aa3bdbdc4. This allows group
auto completion to be used in a plugin's UI.

Change-Id: Ia1cfa068246127c29f1b74f6aa4562a9167c301e

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/api/groups/Groups.java

@@ -63,6 +63,7 @@ public interface Groups {
     private int limit;
     private int start;
     private String substring;
+    private String suggest;
 
     public List<GroupInfo> get() throws RestApiException {
       Map<String, GroupInfo> map = getAsMap();
@@ -128,6 +129,11 @@ public interface Groups {
       return this;
     }
 
+    public ListRequest withSuggest(String suggest) {
+      this.suggest = suggest;
+      return this;
+    }
+
     public EnumSet<ListGroupsOption> getOptions() {
       return options;
     }
@@ -163,5 +169,9 @@ public interface Groups {
     public String getSubstring() {
       return substring;
     }
+
+    public String getSuggest() {
+      return suggest;
+    }
   }
 }