MetadataContributor gets called durcing meta-data building after the first-pass but before the second-pass:

processor.finishUp();
for ( MetadataContributor contributor : classLoaderService.loadJavaServices( MetadataContributor.class ) ) {
  contributor.contribute( metadataCollector, jandexView );
}
metadataCollector.processSecondPasses( rootMetadataBuildingContext );

a lot of things are happening in the second-pass. There should be the possibly to let a MetadataContributor (or a new interface) be called after the second pass.

For example, join columns are only available after the second pass. And it is quite hard to guess their names and do some further processing after the first pass without having those join columns.