code: public final void setHeaderColorStyle(HeaderColorStyle headerColorStyle) {
          this.headerColorStyle = headerColorStyle;
  
          if (!headerColorStyle.getColorStyle().isEmpty()) {
              this.getHeaderLabel().setStyle(headerColorStyle.getColorStyle());
  
              // It's either DEFAULT or CUSTOM value (all empty values)
              // If it is DEFAULT, it sets the default style color
              // Otherwise if it is CUSTOM, by default no style is applied 
              // (default css "generic" color is in play), user has
              // to manually set it via setCustomHeaderColorStyle(String colorStyle)
          } else {
              if (headerColorStyle == HeaderColorStyle.DEFAULT) {
                  switch (this.dialogType) {
                      case INFORMATION:
                          this.updateHeaderColorStyle(HeaderColorStyle.GLOSS_INFO);
                          break;
                      case ERROR:
                          this.updateHeaderColorStyle(HeaderColorStyle.GLOSS_ERROR);
                          break;
                      case WARNING:
                          this.updateHeaderColorStyle(HeaderColorStyle.GLOSS_WARNING);
                          break;
                      case CONFIRMATION:
                          this.updateHeaderColorStyle(HeaderColorStyle.GLOSS_CONFIRM);
                          break;
                      case CONFIRMATION_ALT1:
                          this.updateHeaderColorStyle(HeaderColorStyle.GLOSS_CONFIRM);
                          break;
                      case CONFIRMATION_ALT2:
                          this.updateHeaderColorStyle(HeaderColorStyle.GLOSS_CONFIRM);
                          break;
                      case EXCEPTION:
                          this.updateHeaderColorStyle(HeaderColorStyle.GLOSS_EXCEPTION);
                          break;
                      case INPUT_TEXT:
                          this.updateHeaderColorStyle(HeaderColorStyle.GLOSS_INPUT);
                          break;
                      default:
                          this.updateHeaderColorStyle(HeaderColorStyle.GENERIC);
                          break;
                  }
              }
          }
  
      }
docs: Applies a predefined JavaFX CSS background color style for the header
  label
  
  @param headerColorStyle A <code>HeaderColorStyle</code> option containing
  a color scheme.