Converted writeTrailers to a static method

[gregw]

Fixed TODO regarding making writeTrailers a static method.

[sbordet]

Bit of a mouthful. Can't we just keep it named writeTrailers?
Or perhaps trailersWriter to indicate that it returns a writer that will write the trailers?

[gregw]

I think the new name is good:

• It does not write trailers, it copies them from one HttpFields to another, to be written at a later time.
• If it was just writing/setting trailers, then the signature would be a lot different. It has a very specific signature so that it can be used for a very specific purpose: to be a chunk handler for a copy operation.
• It could perhaps just be asChunkHandler, so that in future other types of chunk might be handled, but I doubt we will ever do that. Having a name that tells us it is used for trailers will help coders looking for a way to handle Trailers chunks

[sbordet]

Handler is so overloaded...

Taking into account your points, how about Response.trailersCopier(Response)?

The "as" in front should be dropped as it is not "converting" the response to something else -- I would tolerate "get" as in getTrailersCopier, but then it creates a new one every time, so newTrailersCopier, but then dropping the prefix make it nicer:

Content.copy(request, response, Response.trailersCopier(response), callback);

[gregw]

But the argument in the copy signature is called chunkHandler, so the names have to match (and that is your name choice in Content!).
I could rename the arg to chunkTransformer? but then this isn't transforming it? or chunkProcessor, but then Processor is overloaded as well.

But regardless, this PR is just about fixing a TODO in the Response class. If you want to change the name of the chunkHandler in the Content class, then do that in a different PR?

[gregw]

closed as we couldn't agree on a name.

[sbordet]

Looks fiiine 🥲, just update the javadocs as suggested 😄

[sbordet]

@gregw more javadoc fixes.