Thanks to Philip Helger for CII to UBL library. I was not able to find UBL to CII, so i have created my own library for the same.
In future planning to release UBL 2.2, UBL 2.3 and CII16A conversions as well.
Converter for EN16931 invoices from UBL2.1 to CII16B
This is a Java 1.8+ library that converts a Universal Business Language (UBL) into a Cross Industry Invoice (CII) document following the rules of the European Norm (EN) 16931 that defines a common semantic data model for electronic invoices in Europe.
This library is licensed under the Apache License Version 2.0.