private MeterIdPrefix meterIdPrefix(SslContextMode mode) {
        MeterIdPrefix meterIdPrefix = this.meterIdPrefix;
        if (meterIdPrefix == null) {
            if (mode == SslContextMode.SERVER) {
                meterIdPrefix = SERVER_METER_ID_PREFIX;
            } else {
                meterIdPrefix = CLIENT_METER_ID_PREFIX;
            }
        }
        return meterIdPrefix;
    }
Returns an {@link SslContext} for the specified {@link SslContextMode} and {@link TlsKeyPair}.
Note that the returned {@link SslContext} should be released via
{@link ReferenceCountUtil#release(Object)} when it is no longer used.
core/src/main/java/com/linecorp/armeria/internal/common/SslContextFactory.java