Bug: Artifact.getClient() returns null

I have a setup where I traverse the whole way from a JenkinsServer to an Artifact (via Job & Build) and all model elements except the Artifact return a proper value for getClient() - the Artifact returns always .

Start by tracing getClient() from JenkinsServer through Job and Build to Artifact, then reproduce the reported traversal and compare the Artifact result with the other model elements. Confirm what client value is expected on Artifact and add coverage for the traversal; done means Artifact.getClient() no longer returns null in that setup.

Written by the indexing model from the issue text.