code: public EncryptedGetObjectRequest withExtraMaterialsDescription(
              Map<String, String> supplemental) {
          setExtraMaterialDescription(supplemental == null ? null
                  : new ExtraMaterialsDescription(supplemental));
          return this;
      }
docs: Fluent API to set the supplemental materials description for the
  encryption materials to be used with the current request.
  
  @param supplemental
  the materialsDescription to set; must not conflict with the
  existing one saved in S3 or else will cause the get request to
  fail fast later on