This is for Sony Xperia Z2 tablet wifi model SGP511 ONLY! It's completely stock to install on locked or unlocked bootloader. You can flash it using flashtool here. It was kinda hard to come by this ftf, that's why I decided to upload it here, so enjoy .
About the firmware:
For: Sony Xperia Z2 Tablet Wifi SGP511
I have tried it myself few times without any issues but I still take no responsibility for your actions.