Change of URL encoding behaviour doesn't seem right

This issue is probably related to #1189 but is focused on the encoding of path variables instead. We've recently upgraded to Spring Cloud to Hoxton.SR3 which includes a bump of Spring Cloud OpenFeign from 2.2.1.RELEASE to 2.2.2.RELEASE. This patch version bumps OpenFeign from 10.4.0 to 10.7.4 which seems to contain quite a few important changes.

In particular, there is a change of behaviour around url encoding (#1138) which in our case has broken a couple of things with using path variables. I've created a sandbox project at https://github.com/sguillope/openfeign-url-encoding-issue to make it easier to reproduce the issue.

The 2 problems we've hit are as follows when using a path variable:

• The colon : character now gets url-encoded to %3A. While not really incorrect, it's not actually required as a colon is a valid character in a path segment (https://tools.ietf.org/html/rfc3986#section-3.3), except for one case which shouldn't apply here. This only broke our integration tests, not production code, so we can easily fix that.
• The most problematic one is the handling of the forward slash / character. With the latest version, it doesn't get url-encoded in path variables. Fortunately this was caught by our integration tests, otherwise it would have broken our production code. We can't pre-encode it because it will then get double-encoded as %252F instead of %2F.

To summarise:

Let me know if you need more details.
Thanks

Start with the linked sandbox project and compare its path-variable encoding with the examples in this issue, while reviewing the related changes in #1189 and #1138. Done means colon handling matches the expected URLs and forward slashes are encoded as %2F without double encoding.