Bug 2172 - AbstractGeneratedTypeBuilder check for duplicate elements.

Check for duplicity of added elements has been added into add* methods
in the AbstractGeneratedTypeBuilder class.

Change-Id: I9ef4caef0a835c0e171e86c2b322c3452bdaada0
Signed-off-by: pkajsa <pkajsa@cisco.com>
Merge "Bug 2172 - AbstractGeneratedTypeBuilder check for duplicate elements."