Question: I am working on project using Java and I'm looking for open source library to parse swift messages: ISO 15022 and 20022.
for 15022 I already find a solution which is Prowidesoftware, but for 20022 I didn't find anything.
any ideas?
thanks.

Answer: 
**November 2020 Update:**

The Prowide ISO 20022 library is now **open source**.
Distributed with Apache license and including features for:

* Java model for ISO 20022 MX (for example: MxPacs00800109 class, for all MX categories)
* Parser from XML into Java model
* Builder API from Java to ISO 20022 XML
* Conversion to JSON
* JPA model for persistence
* Support for multiple application headers: ah$v10, head.001.001.01, head.001.001.02

Info and download at: <https://www.prowidesoftware.com/products/iso20022>

The open source covers all categories, variants and versions of the ISO20022.

While restricted ISO versions such as SEPA, CBPR+, SIC or TARGET are provided as complementary comercial packages.

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I've deleted the outdated previous answer. I'm one of the Prowide libraries authors.
We have searched a lot for this about a year ago, but could not find, so we have made our own parser using XPath.It is a tiresome job, but will be helpful in understanding the structure more closely.