I wrote an article on this a while ago that may be of help.
https://medium.com/mendix/the-new-way-to-call-mendix-microflows-from-java-actions-46152923dbbc
Essentially, it’s just calling the microflowCall method in the Core.
com.mendix.core.Core.microflowCall("TestCallingJava.SUB_ShowMessageCount")
.inTransaction(true)
.withParam("Name", "Donald")
.withParam("MessageCount", "1234")
.execute(this.getContext());
Hope this helps.
You can use the Core.microflowCall method
Core.microflowCall("AModule.SomeMicroflow")
.inTransaction(true)
.withParam("Param1", "Value1")
.withParam("Param2", "Value2")
.execute(context);
Refer to this documentation for more