code: @InterfaceAudience.Public
      public Attachment getAttachment(String name) {
          Map<String, Object> attachmentsMetadata = getAttachmentMetadata();
          if (attachmentsMetadata == null) {
              return null;
          }
          return toAttachment(name, attachmentsMetadata.get(name));
      }
docs: Looks up the attachment with the given name (without fetching its contents yet).