@Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        HttpHeaders that = (HttpHeaders) o;
        return Objects.equals(headers, that.headers);
    }
@return the headers as a map; The map does not support {@code put} or {@code putAll}, nor do
its entries support {@link Entry#setValue setValue}, so you can't use this to add headers.
tika-pipes/tika-fetchers/tika-fetcher-http/src/main/java/org/apache/tika/pipes/fetcher/http/config/HttpHeaders.java