TBEL (ThingsBoard Expression Language) is the expression language behind user-defined functions in the ThingsBoard platform. It is a fork of MVEL 2 adding sandboxing, execution limits, and a few language constructs.
Published as org.thingsboard:tbel.
TBEL is licensed under the Apache License, Version 2.0. See LICENSE for the full license text.
It also contains a vendored copy of the ASM bytecode library under org/mvel2/asm, inherited from MVEL and licensed under the BSD 3-Clause License. See ASM-LICENSE for the full license text.