code: @SdkTestInternalApi
      public void setOverrideDate(Date overriddenDate) {
          if (overriddenDate != null) {
              this.overriddenDate = new Date(overriddenDate.getTime());
          } else {
              this.overriddenDate = null;
          }
      }
docs: Sets the date that overrides the signing date in the request. This method
  is internal and should be used only for testing purposes.