bnormsoftware/fsm4j — pull request #27 by bnorm (2014-07-03 00:32:19+00:00)
Title: Protection against parent state not existing

Fixes #20

When calling the StateBuilder.childOf(...) method, if the specified
parent state does not exist yet in the state machine, a
NullPointerException will be thrown. This change protects against the
null pointer and throws a more specific StateMachineException instead
which describes the problem and how to fix it.