public static int findAvailableTcpPort() {
        return findAvailableTcpPort(PORT_RANGE_MIN);
    }
Find an available TCP port randomly selected from the range [{@value #PORT_RANGE_MIN}, {@value #PORT_RANGE_MAX}].

@return an available TCP port number
@throws IllegalStateException if no available port could be found
grpc-common-spring-boot/src/main/java/net/devh/boot/grpc/common/util/SocketUtils.java