getDeclaredConstructors() return java.lang.NullPointerException

I'm using a java web framework (Vraptor) and I'm having the following problem: The frameworks uses Reflection to instantiate the Controllers parameters, and for some reason one of the Parameters is returing <java.lang.NullPointerException>.

My question is: the framework works normally for a while, and for some reason the "cachedConstructor" of the type I want to instantiate is filled with <java.lang.NullPointerException> instead of what is expected. What could possible make that change?

I'm not asking if the framework is doing this, I just want to know what could do this in Java

getClassType().getDeclaredConstructors() is return java.lang.NullPointerException (returning, not throwing)