public void setDefaultScheme(String defaultScheme) {
        this.defaultScheme = defaultScheme;
    }
Sets the default scheme to use, if the client doesn't specify a scheme/address. If not specified it will default
to the default scheme of the {@link io.grpc.NameResolver.Factory}. Examples: {@code dns}, {@code discovery}.

@param defaultScheme The default scheme to use or null.
grpc-client-spring-boot-starter/src/main/java/net/devh/boot/grpc/client/config/GrpcChannelsProperties.java