CDAP-1047 fixing what looks like a typo which caused dataset
specs to overwrite the types of their child specs. Also adding
some unit tests.
CDAP-1047 remove unintended changes.
CDAP-1047 style changes and add javadoc.
Merge pull request #850 from caskdata/feature/CDAP-1047-fix-ds-spec

Feature/cdap 1047 fix ds spec