Custom connector for connecting 8-pin to 20-pin
This wasn't too hard too find. I am sure there are more.

searched ... 20-pin J-Link connector 8-pin 2x4

This adapter is designed to allow standard 20-pin ARM JTAG devices to connect to the FDI 10-pin mini-JTAG on µEZGUI units and ARM based SOMDIMM units. 



with 100k Pullup to SWDIO and 100k Pulldown to SWCLK