code: public KeysAndAttributes withKeys(java.util.Collection<Key> keys) {
          if (keys == null) {
              this.keys = null;
          } else {
              java.util.List<Key> keysCopy = new java.util.ArrayList<Key>(keys.size());
              keysCopy.addAll(keys);
              this.keys = keysCopy;
          }
  
          return this;
      }
docs: Sets the value of the Keys property for this object.
  <p>
  Returns a reference to this object so that method calls can be chained together.
  <p>
  <b>Constraints:</b><br/>
  <b>Length: </b>1 - 100<br/>
  
  @param keys The new value for the Keys property for this object.
  
  @return A reference to this updated object so that method calls can be chained
  together.