public Builder httpHeader(String key, Collection<String> values) {
            this.configuration.put(ClientConfigProperties.httpHeader(key), ClientConfigProperties.commaSeparated(values));
            return this;
        }
{@see #httpHeader(String, String)} but for multiple values.
@param key - name of the header
@param values - collection of values
@return same instance of the builder
client-v2/src/main/java/com/clickhouse/client/api/Client.java