code: public void errorf(Throwable t, String format, Object param1) {
          if (isEnabled(Level.ERROR)) {
              doLogf(Level.ERROR, FQCN, format, new Object[] { param1 }, t);
          }
      }
docs: Issue a formatted log message with a level of ERROR.
  
  @param t the throwable
  @param format the format string, as per {@link String#format(String, Object...)}
  @param param1 the sole parameter