fix(HttpUtils): Use UTF-8 when forwarding request bodies to OTP

[binh-dam-ibigroup]

Checklist

• Appropriate branch selected (all PRs must first be merged to dev before they can be merged to master)
• Any modified or new methods or classes have helpful JavaDoc and code is thoroughly commented
• The description lists all applicable issues this PR seeks to resolve
• [na] The description lists any configuration setting(s) that differ from the default settings
• All tests and CI builds passing

Description

Looking for advice on unit tests for these changes if practical.

This PR fixes the OTP request maker so that the body content uses UTF-8 encoding to support all international content.

[br648]

The change is good. Not sure how to test this to be honest!

[JymDyerIBI]

Agree, the change looks good. We don't have an HttpUtilsTest class at all, but I'll poke around and see how best to test charsets like this.

It looks like this can be exercised by adding something similar to ApiTestUtils#makePostRequest() and #makePutRequest() methods and exercising those from the unit tests.

[JymDyerIBI]

Digging further, I see that POST and PUT are exercised in ApiUserFlowTest and ConnectedDataPlatformTest unit tests, so I think that should suffice to show that these changes don't break anything.

[JymDyerIBI]

Looks good to me.