request #6449 - Cannot update artifact

Test isEmpty fails for string fields

Change-Id: I1abb97e1ed5907bc69f48611045143a11fe5a31f
Merge commit 'refs/changes/05/2105/1' of http://gerrit.tuleap.net/tuleap into HEAD

* http://gerrit.tuleap.net/tuleap:
  request #6449 - Cannot update artifact

Change-Id: I93e549632b10f20b2739a5bc5ba6dac601a59691
This is Tuleap 6.11.99.13

Change-Id: I3f0914c3bc1bb6549d5f1fc816c91e0356b34461