According to test, #89 is not appliable to equalsToIgnoreCase
Fixes #89 the right way.
In fact, it was not EqualsToIgnoreCase fault, because as a subclass of MonovaluedVertexTest it can call matchesJNull(). No. It was rather VertexPathNavigator which was unable to correctly understand that, even for literals, obtaining the null value is clearly the indication that something went wrong
Better fallback strategy that should avoid any reapparition of #89