Java (J2SE) Bluetooth Low Energy (BLE)

An interesting option is using Kura Bluetooth LE APIs, which are built on top of the TinyB library.

After looking into this a while later I found an answer named TinyB.

https://software.intel.com/en-us/java-for-bluetooth-le-apps

TinyB is a BluetoothLE implementation by Intel and it features a Java SDK. So far I've been able to achieve everything I tried.

Hope this helps others stumbling across this topic.