code: private static Class<?>[] convertParameterTypesToPrimitive(Class<?>[] parameterTypes) {
          Class<?>[] converted = new Class<?>[parameterTypes.length];
          for (int i = 0; i < parameterTypes.length; i++) {
              Class<?> primitiveWrapperType = PrimitiveWrapper.getPrimitiveFromWrapperType(parameterTypes[i]);
              if (primitiveWrapperType == null) {
                  converted[i] = parameterTypes[i];
              } else {
                  converted[i] = primitiveWrapperType;
              }
          }
          return converted;
      }
docs: Convert parameter types to primitive.
  
  @param parameterTypes the parameter types
  @return the class[]