code: private View inflateContentView() {
          if (getRootView() != null) {
              inflateContentContainer();
  
              if (customView != null) {
                  contentContainer.addView(customView);
              } else if (customViewId != -1) {
                  LayoutInflater layoutInflater = LayoutInflater.from(getContext());
                  View view = layoutInflater.inflate(customViewId, contentContainer, false);
                  contentContainer.addView(view);
              }
  
              adaptContentContainerVisibility();
              return contentContainer;
          }
  
          return null;
      }
docs: Inflates the view, which is used to show the dialog's content. The view may either be the
  default one or a custom view, if one has been set before.
  
  @return The view, which has been inflated, as an instance of the class {@link View} or null,
  if no view has been inflated