code: public ListKeysResult withKeys(KeyListEntry... keys) {
          if (this.keys == null) {
              setKeys(new com.amazonaws.internal.SdkInternalList<KeyListEntry>(keys.length));
          }
          for (KeyListEntry ele : keys) {
              this.keys.add(ele);
          }
          return this;
      }
docs: <p>
  A list of customer master keys (CMKs).
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setKeys(java.util.Collection)} or {@link #withKeys(java.util.Collection)} if you want to override the
  existing values.
  </p>
  
  @param keys
  A list of customer master keys (CMKs).
  @return Returns a reference to this object so that method calls can be chained together.