PDI-7243/PDI-11183 - JSON Output Step throws NullPointerException when previewing no rows

PDI-11183 - fixed
PDI-7243 - patch applyed, junit tests
PDI-11183 - junit tests added
PDI-8395 - JSON Output step only outputs last line of transformation if
append is not checked.

junit tests added
PDI-8395 - JSON Output step only outputs last line of transformation if
append is not checked.

fix added
PDI-7243 - JSON Output Step throws NullPointerException when previewing
no rows

Fix patch to be compatible with old behaviour
Checkstyle for junit test, System.out removed