protected static io.grpc.netty.shaded.io.grpc.netty.NegotiationType of(final NegotiationType negotiationType) {
        switch (negotiationType) {
            case PLAINTEXT:
                return io.grpc.netty.shaded.io.grpc.netty.NegotiationType.PLAINTEXT;
            case PLAINTEXT_UPGRADE:
                return io.grpc.netty.shaded.io.grpc.netty.NegotiationType.PLAINTEXT_UPGRADE;
            case TLS:
                return io.grpc.netty.shaded.io.grpc.netty.NegotiationType.TLS;
            default:
                throw new IllegalArgumentException("Unsupported NegotiationType: " + negotiationType);
        }
    }
Converts the given negotiation type to netty's negotiation type.

@param negotiationType The negotiation type to convert.
@return The converted negotiation type.
grpc-client-spring-boot-starter/src/main/java/net/devh/boot/grpc/client/channelfactory/ShadedNettyChannelFactory.java