presto-cli/src/main/java/io/prestosql/cli/ClientOptions.java/ClientOptions/toExtraCredentials
class ClientOptions:    public static Map<String, String> toExtraCredentials(List<ClientExtraCredential> extraCredentials)
    {
        ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();
        for (ClientExtraCredential credential : extraCredentials) {
            builder.put(credential.getName(), credential.getValue());
        }
        return builder.build();
    }