Cannot connect to ESXi 6.5 VNC server

I was having trouble getting Guacamole to connect to ESX 6.5's VNC server. The issue is reported here - https://github.com/LibVNC/libvncserver/issues/141

Using TightVNC, TigerVNC, UltraVNC, and Chicken of the VNC the connection worked fine - only Guacamole failed. After some Wireshark sleuthing I found that libvncserver's client by default sets the trueColour flag to TRUE (which is -1 which is 255), whereas all of the other clients listed above set this flag to 1. Although the spec is vague - it says non-zero is "true" - I would suggest setting this flag to 1 to maximize compatibility:

void guac_vnc_set_pixel_format(rfbClient* client, int color_depth) {
    client->format.trueColour = 1;