GCP deployment handler name issue (with dot) for java functions

I am trying to deploy an existing aws serverless stack to gcp, it is currently implemented by using java8.

I did a couple of tests by using python and it works. But I changed the handler to java class

So please advice when it is supported or any work-round for this issue?

The output

Error: The "handler" property for the function "bsFileTransferInitProcessor" is invalid. Handlers should be plain strings referencing only the exported function name without characters such as "." or "/" (so e.g. "http" instead of "index.http"). Do you want to nest your functions code in a subdirectory? Google solves this by utilizing the "main" config in the projects package.json file. Please check the docs for more info.
      at /home/leo/workspace/data-receipt-station/node_modules/serverless-google-cloudfunctions/shared/validate.js:50:15
      at /home/leo/workspace/data-receipt-station/node_modules/lodash/lodash.js:4925:15

Installed version

Framework Core: 1.58.0
Plugin: 3.2.5
SDK: 2.2.1
Components Core: 1.1.2
Components CLI: 1.4.0