add Java reproducible builds paper

Author: algomaster99

index.md

@@ -44,6 +44,7 @@ To get notified about project news, subscribe to the [Chains mailing list](https
 (reverse chronological order, newest first)
 
 * 2025
+  - [Canonicalization for Unreproducible Builds in Java](https://arxiv.org/abs/2504.21679), Technical report 2504.21679, arXiv, 2025.
   - [Implementing SBOM Attestations in an Enterprise Context](todo), Master's thesis Christofer Vikström, 2025
   - [Software Bills of Materials in Maven Central](https://arxiv.org/abs/2501.13832), Proceedings of MSR 2025.
   - [On-Chain Analysis of Smart Contract Dependency Risks on Ethereum](http://arxiv.org/pdf/2503.19548), Technical report 2503.19548, arXiv, 2025.