Currently I see no way to apply custom Elasticsearch-defined analyzers on extra fields defined in class bridges.

With Lucene it is possible to do it as described here. In that article 'Solution 2' solves it using a custom analyzer implementation defined in the local code. In my case the analyzer is defined in Elasticsearch and I could not find a way to access the analyzer definition from the internal analyzer registry. 'Solution 3' relies on analyzer configuration defined by @AnalyzerDef which does not solve this issue for remotely-defined analyzers.

My use case:
I have a custom Elasticsearch index with custom analyzer definitions. I have a class bridge that adds document fields that need to be analyzed with the custom analyzers.

See related ticket here