Improve work with SSL/TLS certificates in SDK IO, for Google Dataflow

Sinks like Kafka or Elasticsearch have worked with SSL/TLS. But all of these can read only certificates from a local machine (use java.io.File#File(java.lang.String). 
In the case of Google Dataflow, we can not easily copy files to a worker, I see two possible variants to read certificates from the worker:
1) somehow copy certificates to a worker from GC Storage 

2) in Kafka IO or Elasticsearch IO read certificates directly from GC Storage 

Any thoughts about how I can solve this issue easily or mb other variants will be helpful.