Stop redirect loops

[asf-stripe]

It's possible for a misconfigured HTTP server to redirect /a to /b and /b back to /a. Most HTTP clients stop following redirects after a few. We've arbitrarily chosen 20 in the failing test at 0f292f4.

You can run only this test with

mvn test -Dsurefire.useFile=false '-Dtest=CallTest#doesNotFollow21Redirects' -DfailIfNoTests=false

Make sure the follow20Redirects test continues to pass.

IntelliJ IDEA tips:
Make sure you run mvn generate-sources before opening in IDEA.
If you're reading this too late, right-click the okhttp project > Maven > Generate Sources and Update Folders.