Add a no arg constructor for request grouping

src/main/java/io/vertx/redis/client/RequestGrouping.java

@@ -1,7 +1,9 @@
 package io.vertx.redis.client;
 
 import io.vertx.codegen.annotations.DataObject;
+import io.vertx.codegen.annotations.GenIgnore;
 
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Objects;
@@ -14,9 +16,15 @@
  */
 @DataObject
 public class RequestGrouping {
+
   private final Collection<List<Request>> keyed;
   private final List<Request> unkeyed;
 
+  public RequestGrouping() {
+    this.keyed = new ArrayList<>();
+    this.unkeyed = new ArrayList<>();
+  }
+
   public RequestGrouping(Collection<List<Request>> keyed, List<Request> unkeyed) {
     this.keyed = Objects.requireNonNull(keyed);
     this.unkeyed = Objects.requireNonNull(unkeyed);
@@ -29,6 +37,7 @@ public RequestGrouping(Collection<List<Request>> keyed, List<Request> unkeyed) {
    * Does not include any request that doesn't specify a key; use {@link #getUnkeyed()}
    * to get those.
    */
+  @GenIgnore
   public Collection<List<Request>> getKeyed() {
     return keyed;
   }
@@ -37,6 +46,7 @@ public Collection<List<Request>> getKeyed() {
    * Returns a collection of requests that do not specify a key and would therefore
    * be executed on random node.
    */
+  @GenIgnore
   public List<Request> getUnkeyed() {
     return unkeyed;
   }