Avoid exposing internal SideInput Constants to end users

[KeranYang]

The SideInput Constants class is exposed to user because we expect the user to use the directory. Constants other than directory should not be exposed.

It will be technically a backward-incompatible change. Will choose the right time/version to fix this issue.

[yhl25]

Since the Constants class itself is package-private, How will the constants be exposed to the users?

[KeranYang]

@yhl25 Please see this example, it is directly accessing the Constant - https://github.com/numaproj/numaflow-java/blob/main/examples/src/main/java/io/numaproj/numaflow/examples/sideinput/udf/SimpleMapWithSideInput.java#L34

[yhl25]

That was because the Constants class was public for sideInput.

[KeranYang]

Thanks! I updated the issue description.

[KeranYang]

NVM, the other constants are NOT exposed to user because they are not public. I am closing this issue. cc: @yhl25 sorry about the misleading description.