[Java][Docs] Undocumented null return from CallHeaders.getAll()

[indigophox]

Describe the bug, including details regarding any error messages, version, and platform.

The Java CallHeaders documentation doesn't document that .getAll() will return null if no matches are found, so the reader is left with the default assumption of getting back an empty Iterator<>.

I assume this probably extends to .getAllByte() but I haven't had time to investigate yet.

I will probably fix the documentation in the near future, although (given it's theoretically not a breaking change—there is no guarantee of not receiving an empty Iterator<> either!) I'm somewhat more inclined to change the behaviour to eliminate the null check anywhere it's used, unless anyone objects.

Component(s)

Java, Documentation

[vibhatha]

@indigophox thanks for reporting this one. Seems reasonable to me.