default Optional<String> getDefaultValueFromEnvVar() {
        String value = System.getenv(getEnvironmentVariable());
        if (value != null) {
            value = value.trim();
        }
        return Optional.ofNullable(value);
    }
Gets trimmed default value from environment variable. By default the
environment variable is named as {@link #getPrefix()} + "_" + {@link #name()}
in upper case.

@return trimmed default value defined in environment variable
clickhouse-data/src/main/java/com/clickhouse/config/ClickHouseOption.java