SSH option preparation

[slavino]

preparing SSH support

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[michael-o]

I would recommend to collect all SSH private key related issues to one JIRA issue and create ONE PR for it.

[slavino]

I don't have access to your JIRA so feel free.

The contribution isn't any rocket science at this stage but shouldn't break anything (backward compatibility shouldn't be affected). If needed then feel free to delete these PRs and create a new one.

Before announcing it as new feature it will need to be covered by proper tests. Afterwards it can also be mentioned in the official plugin documentation.

[michael-o]

JIRA is available to everyone: https://issues.apache.org/jira/projects/MRELEASE/issues/MRELEASE-1079?filter=allopenissues
This are a bit harder because it will required to setup SSHd with MINA and test that.

[scott-avery]

any update for this? We encounter a problem that the registered ssh private key is not used by the plugin.

[kwin]

This is already implemented in 7f60b4e. Currently passphrase cannot be parameterized though, look at apache/maven-scm#1222 for a reasoning.