protected IOException logIOException(
      String configKey, Level logLevel, IOException ioe, long elapsedTime) {
    log(
        configKey,
        "<--- ERROR %s: %s (%sms)",
        ioe.getClass().getSimpleName(),
        ioe.getMessage(),
        elapsedTime);
    if (logLevel.ordinal() >= Level.FULL.ordinal()) {
      StringWriter sw = new StringWriter();
      ioe.printStackTrace(new PrintWriter(sw));
      log(configKey, "%s", sw.toString());
      log(configKey, "<--- END ERROR");
    }
    return ioe;
  }
Override to filter out response headers.

@param header header name
@return true to log a response header
core/src/main/java/feign/Logger.java