[Java]: Correct logic for dealing with returning default values when a message extension.

Author: mjpt777

examples/java/uk/co/real_logic/sbe/examples/ExampleTokenListener.java

@@ -219,7 +219,7 @@ private static PrimitiveValue constOrNotPresentValue(final Token token, final in
  }
  else if (Encoding.Presence.OPTIONAL == encoding.presence())
  {
- if (token.version() < actingVersion)
+ if (actingVersion < token.version())
  {
  return encoding.applicableNullValue();
  }