code: public static Field[] fields(Class<?> clazz, String[] fieldNames) {
          return Whitebox.getFields(clazz, fieldNames);
      }
docs: Get an array of {@link Field}'s that matches the supplied list of field
  names.
  
  @param clazz
  The class that should contain the fields.
  @param fieldNames
  The names of the fields that will be returned.
  @return An array of Field's. May be of length 0 but not {@code null}