A JSONPatch-enabled API requires validation logic which will check the
correctness of incoming request body according to schema. A mixin is
added which will do such validations.
Such validation logic may be useful not only for Artifacts API but also
for regular v2 images API, as it also uses JSONPatch notation in its
update calls. So this mixin may be used in future in Images API as well.
Implements-blueprint: artifact-repository
Change-Id: I1b7b72bcc0a0455803a4e99dd17a9732b0dd7a8d
65682fc81a