public Builder setProxyCredentials(String user, String pass) {
            this.configuration.put("proxy_user", user);
            this.configuration.put("proxy_password", pass);
            return this;
        }
Sets the default database name that will be used by operations if not specified.
@param database - actual default database name.
client-v2/src/main/java/com/clickhouse/client/api/Client.java