code: public void setKeys(java.util.Collection<String> keys) {
          if (keys == null) {
              this.keys = null;
              return;
          }
  
          this.keys = new java.util.ArrayList<String>(keys);
      }
docs: <p>
  The keys that are included in this group.
  </p>
  
  @param keys
  The keys that are included in this group.