public static CapabilityMode getCapabilityMode() {
        return getEnvironmentVariable(System.getenv(), CAPABILITIES_ENV_VAR)
                .map(CapabilityMode::fromConfigValue)
                .orElse(CapabilityMode.defaultValue());
    }
Utility class for retrieving {@link TransportSecurityOptions} from the system.

@author bjorncs
security-utils/src/main/java/com/yahoo/security/tls/TransportSecurityUtils.java