docs: public static String toStringWithRootCause(@Nullable Throwable t) {
  		if (t == null) {
  			return StringUtils.EMPTY;
  		}
  
  		final String clsName = ClassUtils.getShortClassName(t, null);
  		final String message = StringUtils.defaultString(t.getMessage());
  		Throwable cause = getRootCause(t);
  
  		StringBuilder sb = new StringBuilder(128).append(clsName).append(": ").append(message);
  		if (cause != t) {
  			sb.append("; <---").append(toStringWithShortName(cause));
  		}
  
  		return sb.toString();
  	}