There is an error in the Adafruit GFX I2C examples for mbed

oled.cpp

#include "mbed.h"
#include "Adafruit_SSD1306.h"

// Instantiate OLED
class I2CPreInit : public I2C
{
public:
    I2CPreInit(PinName sda, PinName scl) : I2C(sda, scl)
    {
        frequency(400000);
        //start(); This broke I2C
    };
};

I2CPreInit gI2C(PB_9, PB_8);
Adafruit_SSD1306_I2c gOled1(gI2C, D13, 0x78,64,128);