Define and add updates needed to run a simple Java transform using Python SDK on top of the reference runner (ULR) #18862
Description
Task here is the do research and perform updates necessary to run a simple Java transform that does not require expansion through Beam portability offering. Initially we'll try to get this working for ULR and will try to expand into other runners later.
This will also including coming up with a reasonable mechanism to define a shim in SDK A for a transform that is fully defined in SDK B.
This should be combined with efforts to introduce mechanisms to expand cross platform transforms (see [1]) to achieve a full cross language transform offering which will, for example, allow IOs defined in SDK B to be used in SDK A.
[1] https://s.apache.org/beam-mixed-language-pipelines
Imported from Jira BEAM-3923. Original Jira may contain additional context.
Reported by: chamikara.