FMI4j is a new open-source Kotlin library that allows import and simulation of Model Exchange and Co-simulation FMUs compliant with the FMI 2.0 standard.
As Kotlin is 100% interoperable with Java, its up to the end user which language to use.
As of late 2017, Fmi4j is the only Java library that support Model Exchange 2.0.
Fmi4j don’t just import such FMUs, but can also solve them using the integrators available in Apache Commons Math.
Fmi4j uses the gradle build system, allowing you to easily set it up on your own machine.
FYI: I am the library author