private static String normalize(String key, String separator, boolean upperCase) {
    String result = key.replaceAll("[._-]", separator);
    return upperCase ? result.toUpperCase(Locale.ROOT) : result.toLowerCase(Locale.ROOT);
  }
Returns arguments parsed from command-line arguments, JVM properties, environmental variables.
<p>
Priority order:
<ol>
<li>command-line arguments: {@code java ... key=value}</li>
<li>jvm properties: {@code java -Dplanetiler.key=value ...}</li>
<li>environmental variables: {@code PLANETILER_KEY=value java ...}</li>
</ol>

@param args command-line args provide to main entrypoint method
@return arguments parsed from those sources
planetiler-core/src/main/java/com/onthegomap/planetiler/config/Arguments.java