Made ProductTransformer work with heterogeneous data

Bug fix: [yes|no]
Feature addition: [no]
Backwards compatibility break: [yes]
Unit test passes: [yes]
Specs passes: [yes]
Replaced unit test classes removed: [yes]
Behat scenario passes: [yes]
Checkstyle issues: [no]*
ChangeLog updated: [no]
Documentation PR: [link to the documentation PR if there is one]
Fixes the following jira:

ProductTransformer is now able to work with heterogeneous data.