code: public void setValidUserList(java.util.Collection<String> validUserList) {
          if (validUserList == null) {
              this.validUserList = null;
              return;
          }
  
          this.validUserList = new com.amazonaws.internal.SdkInternalList<String>(validUserList);
      }
docs: <p>
  A list of users or groups in the Active Directory that are allowed to access the file share. A group must be
  prefixed with the @ character. For example <code>@group1</code>. Can only be set if Authentication is set to
  <code>ActiveDirectory</code>.
  </p>
  
  @param validUserList
  A list of users or groups in the Active Directory that are allowed to access the file share. A group must
  be prefixed with the @ character. For example <code>@group1</code>. Can only be set if Authentication is
  set to <code>ActiveDirectory</code>.