How do I represent complex Map as parameter argument for Class.declaredMethod parameterType?

I have a private method I need to access from a junit. The method has the following signature:

private String search(Map<String, String[]> params, String userName) 

I have tried the following setup:

Method mockSearch;
Class[] cArg = new Class[2];

cArg[0] = Map<String, String[]>.class  
cArg[1] = String.class;
mockSearch = aClass.getClass().getDeclaredMethod("search", cArg);

Which obviously won't even compile because "cArg[0] = Map<String, String[]>.class" is nonsensical. So I attempted a concrete class for arg 0 like this:

Map<String, String[]> mockMap = new HashMap<>();
cArg[0] = mockMap.getClass();

which threw exception at runtime because of the strictness of the getDeclaredMethod. Here basically is exception snippet:

java.lang.NoSuchMethodException: blah.blah.blah$MyTestClass.search(java.util.HashMap, java.lang.String)

Is there a way to represent a Map<String, String[]> class type that will work? Thanks for ideas.