Apache projects provide implementations for many open standards. Some of these are reference implementations. A list of implementations is maintained at projects.apache.org.
Note that the ASF no longer participates directly in the Java Community Process (JCP).
Please see our open letter and FAQ..
Guides are available for projects that want to get involved with standards processes:
An implementation of an open standard that is accepted by the standards body as canonical.
See this.
Apache projects create DOAP files that describe the software and any standards they implement.