Allow masking custom headers

[amarruedo]

Would you take this in consideration?

Sometimes custom headers are filled with authentication tokens, and it would be nice if those tokens do not appear in the logs.

This pipeline script:

#!groovy

httpRequest httpMode: 'GET', 
       customHeaders: [[name: 'X-Vault-Token', value: vault_token, maskValue: true],[name: 'X-Test', value: 'test']], 
       url: http://vault.default.svc.cluster.local:8200/v1/secret/mySecret

would output the folowing in the logs:

[Pipeline] httpRequest
HttpMode: GET
URL: http://vault.default.svc.cluster.local:8200/v1/secret/android_debug
Content-type: application/json
X-Vault-Token: *****
X-Test: test
Sending request to url: http://vault.default.svc.cluster.local:8200/v1/secret/mySecret
Response Code: HTTP/1.1 200 OK
Success code from [100‥399]

The default behaviour is to not mask the value, so the extra maskValue parameter is only required when you need to mask the value.

I've tested this on my local Jenkins (v 2.32.1) succesfully. I'm not java nor Jenkins plugin developer so it's possible that there is a better way to achieve this, but anyway, here are my two cents.

[janario]

Thanks for the pull request.

I'm going to do some more tests local and release it soon.