public SELF maskingFunction(HeaderMaskingFunction maskingFunction) {
        this.maskingFunction = requireNonNull(maskingFunction, "maskingFunction");
        return self();
    }
Sets the {@link Function} to use to maskFunction headers before logging.
The default maskingFunction is {@link HeaderMaskingFunction#of()}

<pre>{@code
builder.maskingFunction((name, value) -> {
  if (name.equals(HttpHeaderNames.AUTHORIZATION)) {
    return "****";
  } else if (name.equals(HttpHeaderNames.COOKIE)) {
    return name.substring(0, 4) + "****";
  } else {
    return value;
  }
}
}</pre>
core/src/main/java/com/linecorp/armeria/common/logging/AbstractHeadersSanitizerBuilder.java