fix: encode plus sign in url with %2B by ldetmer · Pull Request #2094 · googleapis/google-http-java-client

Currently we are not encoding + signs if it part of the URL path, while this is to spec

Thus, only alphanumerics, the special characters "$-_.+!*'(),", and
reserved characters used for their reserved purposes may be used
unencoded within a URL.

It MAY be encoded.

Originally we did encode plus signs, but inappropriately as a space (%20). This was fixed in this PR . However the fix did 2 things, it stopped treating the + sign as a space, but it also stopped encoding it at all. Technically it only need the first fix here. Removing encoding of the + sign caused several APIs to stop working (spreadsheets and gmail).

So this fix is to bring back converting + signs, however due to the original fix, it now converts them correctly to %2B (+), not %20 (space)

Note we still do NOT want + signs to be encoded for SAFEPATHCHARS_URLENCODER, as we still want to utilize it for reserved expansions See issue

Tested: gmail apiary, sheets apiary, storage apiary and gapic

Fixes #20415
Fixes #1573