code: private boolean notifyOnChildClicked(@NonNull final View view, final int groupIndex,
                                           final int childIndex, final long id) {
          return childClickListener != null &&
                  childClickListener.onChildClick(this, view, groupIndex, childIndex, id);
      }
docs: Notifies the listener, which has been registered to be notified, when a child has been
  clicked, about a child being clicked.
  
  @param view
  The view within the expandable grid view, which has been clicked, as an instance of
  the class {@link View}. The view may not be null
  @param groupIndex
  The index of the group, the child, which has been clicked, belongs to, as an {@link
  Integer} value
  @param childIndex
  The index of the child, which has been clicked, as an {@link Integer} value
  @param id
  The id of the child, which has been clicked, as a {@link Long} value
  @return True, if the click has been handled by the listener, false otherwise