public AbstractHttpFileBuilder entityTag(boolean enabled) {
        entityTagFunction = enabled ? DefaultEntityTagFunction.get() : null;
        return this;
    }
Sets whether to set the {@code "etag"} header automatically based on the path and attributes of the
file. By default, the {@code "etag"} header is set automatically. Use {@link #entityTag(BiFunction)} to
customize how an entity tag is generated.
core/src/main/java/com/linecorp/armeria/server/file/AbstractHttpFileBuilder.java