code: public static Class<?> wrap(final Class<?> type) {
  	if (!type.isPrimitive()) {
  	    throw new IllegalArgumentException("Not primitive");
  	}
  	return PRIMITIVES_WRAPPERS.get(type);
      }
docs: Gets the wrapper type for the primitive type.
  
  @param type
  Primitive type to wrap.
  @return The primitive wrapper type.
  @throws IllegalArgumentException
  If the type is not primitive.