BUG-1097: implemented check for null or empty list in builder classes.

If one of builder variable is List, do following:
 - for null value create Collections.emptyList()
 - for empty list create Collections.emptyList()
 - for any other list create ImmutableList.copyOf(<arg>)

Added test.

Change-Id: I83e5aaf4f4253aa2e195c23ff5b48b04fc883052
Signed-off-by: Martin Vitez <mvitez@cisco.com>